Abstract
Endometrial-derived uterine histotroph is a critical component of nutrient supply to a growing conceptus throughout gestation; however, the effect of nutritional plane on histotroph nutrient composition remains unknown in multiparous cows. We hypothesized that differing planes of nutrition would alter histotroph and serum nutrient composition in beef cattle. Thus, we evaluated serum and histotroph amino acid and glucose composition, and serum non-esterified fatty acids (NEFA) and blood urea nitrogen (BUN) in cows individually fed to maintain body weight (BW; 0 kd/d, n = 9; CON) compared with those losing moderate BW (−0.7 kg/d, n = 9; NEG). After 49 d of differing nutritional planes, cows were subjected to the 7-d CoSynch + controlled internal drug release device estrus synchronization protocol and then slaughtered on day 62. Blood serum (days 0 and 62) and uterine histotroph [day 62; from uterine horns ipsilateral and contralateral to the corpus luteum (CL)] were collected and analyzed for concentrations of amino acids, glucose, and NEFA. Performance characteristics, body composition via ultrasound (days 0 and 62), and carcass characteristics were collected. Body condition score, change in BW, average daily gain, dry matter intake, and gain:feed were decreased (P ≤ 0.05) in NEG vs. CON cows. There were no differences in body composition or carcass characteristics, except an increase (P ≤ 0.05) in dressing percentage in NEG cows due to differences in gut fill, consistent with study design. Serum NEFA increased (P ≤ 0.05) in the NEG group, but there were no differences between NEG vs. CON in glucose or BUN. Serum histidine increased (P ≤ 0.05) and alanine, isoleucine, and tryptophan decreased (P ≤ 0.05) in NEG vs. CON cows. Compared with that of the uterine horn ipsilateral to the CL, histotroph from the uterine horn contralateral to the CL had increased (P ≤ 0.05) isoleucine, asparagine, and proline concentrations in NEG cows, and decreased (P ≤ 0.05) tryptophan as a proportion of essential and total amino acids. There were no differences in glucose concentrations of histotroph contralateral or ipsilateral to the CL. Cow nutritional plane does alter serum and histotroph amino acid composition, although the presence of an embryo may be necessary to fully elucidate these changes. Differences in serum and histotroph tryptophan should be given consideration in future studies due to its importance as an essential amino acid in protein synthesis and bioactive affects.
Keywords: beef cows, circulating nutrients, growth and development, performance, periconceptual nutrition, uterine fluid
This study reports the effect of differing nutritional planes on alterations in serum and uterine histotroph amino acid composition in nonpregnant, multiparous beef cows. BW loss may alter uterine histotroph, affecting growth and development of the conceptus during establishment of pregnancy.
Introduction
Oviductal fluid is comprised of glucose, lactate, pyruvate, amino acids, and proteins derived from epithelium and blood plasma, which have significant impacts on oocyte maturation, zona pellucida hardening, fertilization, and embryo growth (Avilés et al., 2010; Coy and Yanagimachi, 2015; González-Brusi et al., 2020). Furthermore, upon reaching the blastocyst stage and entering the uterus, endometrial-derived histotroph, composed of enzymes, growth factors, adhesion proteins, cytokines, hormones, glucose, fructose, amino acids, and fatty acids, is necessary for conceptus growth, development, and survival (Mullen et al., 2012; Artus et al., 2020). Endometrial glands remain functional throughout gestation, undergoing hyperplasia and hypertrophy, to supply histotroph to the placenta for sustained conceptus growth and development (Spencer and Bazer, 2004; Spencer et al., 2019). While the importance of uterine histotroph on conceptus growth and development has been demonstrated across mammalian species the impact of perturbations in histotroph on the uterine environment upon entrance of the embryo remains unknown.
The phenomena of postpartum negative energy balance leading up to the breeding season creates a challenge in maintaining a 12-month calving interval, which is vital for production efficiency and profitability of cow–calf operations. Protein alterations in the pre-implantation uterine environment results in pregnancy failure, ultimately extending the calving interval (Martins et al., 2018). Maternal diet alterations have been shown to alter the amino acid composition of uterine histotroph and impact the pre-implantation proteome of the conceptus during the luteal phase (Eckert et al., 2012; Kermack et al., 2015; Harlow et al., 2018). Similarly, maternal undernutrition during the periconceptual period, including pre-breeding nutrition, decreases oocyte cleavage, morula and blastocyst formation, and causes pre-term delivery in sheep (Bloomfield et al., 2003, 2004; Kumarasamy et al., 2005; Grazul-Bilska et al., 2012). Similarly, the absence of glutamine and high concentrations of essential amino acids in bovine embryo culture negatively impacted development (Steeves and Gardner, 1999). Additionally, amino acid composition is altered in fetal fluids from early and late gestation cows subjected to nutrient restriction (Crouse et al., 2019; Swanson et al., 2022). The aforementioned in vitro studies demonstrate the importance of reproductive tract fluid composition in proper conceptus growth and development; however, there are relatively few in vivo studies in cattle, creating a need to understand the role of nutrition on histotroph nutrient composition in beef cattle.
We hypothesized that differing planes of nutrition alter histotroph and serum nutrient composition in beef cattle. Thus, we evaluated the amino acid (AA) and glucose composition of serum and uterine histotroph, as well as serum non-esterified fatty acids (NEFA) and blood urea nitrogen (BUN) in cows maintaining body weight (BW) vs. cows exhibiting moderate loss of BW.
Materials and Methods
All procedures were approved by the North Dakota State University Institutional Animal Care and Use Committee.
Animals and experimental design
Eighteen multiparous, nonpregnant cows averaging 6.15 ± 0.9 yr of age, 598.15 ± 23.6 kg BW and a body condition score (BCS; Wagner et al., 1988) of 5.36 ± 0.08 on a 9-point scale were enrolled in this study at the North Dakota State University Animal Nutrition and Physiology Center in 2 replicate groups (n = 9/replicate). Within each group, cows were ranked by BW and randomly assigned to differing planes of nutrition: maintain BW (i.e., no change in BW, n = 9; CON) or moderate BW loss (−0.7 kg/d, n = 9; NEG). Cows were fed-to-gain targets individually with initial projections based upon NASEM (2016) requirements. Diets were a limit fed, total mixed ration (approximately 8.7% crude protein and 48% neutral detergent fiber) consisting of 78.9% corn silage, 19.8% mixed-grass hay, and 1.3% mineral supplement in a dried distillers grains plus solubles carrier. Diets were fed once daily via a Calan feeding system (American Calan, Northwood, NH, USA) and cows had ad libitum access to fresh water for 62 d. All cows received the same diet in amounts that were adjusted to maintain or lose BW on an individual basis weekly.
Weekly BW were collected and used to calculate dietary intake for the targeted rate of BW change for each group. Average daily gain (ADG) was calculated as (final BW, kg − initial BW, kg) ÷ 62 d. Body condition scores were collected on days 1 and 62, and change in BCS was calculated as final BCS—initial BCS. Body composition traits of 12th rib subcutaneous fat thickness, 12th rib longissimus muscle area, 12th rib marbling, and rump fat were evaluated on days 0 and 62 via ultrasonography (Wall et al., 2004). Feed intake was recorded daily (DM basis), and gain:feed (G:F) was calculated as (final BW, kg − initial BW, kg) ÷ total feed intake DM, kg.
Blood collection
Blood samples were collected via coccygeal venipuncture on days 0 and 62 into 10-mL silicone-coated and 10-mL sodium heparin-coated tubes (BD Vacutainer, Franklin Lakes, NJ) for serum and plasma, respectively. Serum samples were allowed to clot on ice for 30 min, and then all blood samples were centrifuged at 1,500 × g for 30 min at 4 °C. Serum and plasma were separated from the remaining blood constituents, and aliquots were stored in 2-mL tubes at −20 °C until analysis.
Estrus synchronization
Cows were subjected to the 7-d CO-Synch + controlled internal drug releasing (CIDR; Eazi-Breed CIDR, Zoetis, Parsippany, NJ, USA) estrus synchronization protocol (Lamb et al., 2010). Beginning on d 49 of the trial, cows received a 2-mL i.m. injection of gonadotropin-releasing hormone (GnRH; Factrel, 50 µg gonadorelin hydrochloride/mL, Zoetis) and a CIDR. After 7 d, CIDRs were removed and cows received a 5-mL i.m. injection of prostaglandin F2α (Dinoprost tromethamine, 5 mg/mL, Zoetis). Sixty-six hours later, cows received a 2-mL i.m. injection of GnRH.
Slaughter procedures
At the end of the 62 d dietary treatment, and 3 d after estrus, cows were slaughtered at a federally inspected facility via captive bolt stunning and exsanguination. After slaughter, the entire reproductive tract was obtained from each cow and transported on ice to the laboratory for further processing. To prepare the uterine horns for flushing, the adnexa was removed and the horns were separated from each other by cutting the broad ligament from the external bifurcation to the internal bifurcation. The cranial portion of the target flushing site on each horn was the utero-tubular junction (UTJ), which was isolated by clamping the uterus with forceps just caudal to the UTJ, then the oviduct was removed from the uterus cranial to the forceps. The histotroph flush site was isolated by clamping across each uterine horn at a distance 12 cm caudal to the forceps placed at the UTJ. A scissor was used to cut through the perimetrium at a distance 2 cm from the caudal clamp, then a bovine in vitro fertilization catheter was used to blunt dissect through the myometrium and endometrium and into the uterine lumen. To collect uterine histotroph, a flush was conducted for the uterine horns both ipsilateral and contralateral to the developing corpus luteum (CL). The flush was conducted by dispensing 2.5 mL of saline into the uterine lumen and gently massaging for 30 s. The saline was recovered by removing the cranial forceps and squeezing the fluid out of the horn into a sterile petri dish. This procedure was repeated for a total of 2 flushes and 5 mL of saline per uterine horn. After collection, the histotroph flush was centrifuged at 1,000 × g for 10 min at 4 °C. The supernatant was removed, aliquoted, and stored at −80 °C until analysis.
Carcass characteristics
At slaughter, hot carcass weight (HCW) was recorded and dressing percentage was calculated: HCW ÷ live BW. After a 24 h chill, carcass backfat thickness and ribeye area (REA) were collected between the 12th and 13th rib, and percentage kidney, pelvic, and heart fat (KPH) was measured. Yield grade (YG) was calculated: 2.50 + (2.5 × backfat thickness, inches) + (0.2 × KPH, %) + (0.0038 × HCW, lbs)—(0.32 × REA, in.2; Bertelsen, 2019).
Serum analyses
Concentrations of serum amino acids, glucose, NEFA, and blood urea nitrogen were determined on days 0 and 62.
Concentrations of the 20 most common AA were determined using an ACUITY Ultra Performance Liquid Chromatograph (UPLC; Waters Corporation, Milford, MA, USA), as described by (Lemley et al., 2013) using 250 µM norvaline as an internal standard for each sample. Briefly, 250 µL of serum was deproteinized with 250 µL of 10% sulfosalicylic acid. Deproteinized samples were derivatized with MassTrac Amino Acid Analysis reagent (Waters Corporation) and heated at 55 °C for 10 min then injected into the UPLC. The change in concentrations of serum AA was calculated as: day 62 AA concentration – day 0 AA concentration, µmol/L. Individual AA as a percentage of total AA was calculated as: (AA concentration − total AA concentration, µmol/L) × 100. Change in individual AA concentration as a percentage of total AA was calculated as: day 62 AA percentage of total AA − day 0 AA percentage of total AA, %.
Concentrations of glucose were determined in serum by using a colorimetric assay as described by Lektaz et al. (2010). In brief, samples were compared with the standard curve after the average absorbance of the blank was subtracted from all standards and samples. Accutrol (Sigma, St. Louis, MO, USA) was used as a standardized control sample across plates. Plates were incubated in a Synergy H1 Microplate Reader (Biotek, Winooski, VT, USA) at 37 °C for 15 min, and absorbance was read at 340 nm. Inter and intraassay CV were 8.2% and 2.8%, respectively. Change in glucose concentration was calculated as day 62 glucose concentration − day 0 glucose concentration, mg/dL.
Concentrations of NEFA in serum were measured in duplicate using a colorimetric assay at an absorbance of 550 nm with the Acyl-CoA synthetase-acyl-CoA oxidase method (NEFA HR 2, Fujifilm Wako Diagnostics, Mountain View, CA, USA). In brief, samples were compared with the standard curve after the average absorbance of the blank was subtracted from all standards and samples. A NEFA standard solution (Fujifilm Wako Diagnostics) was used as an internal control. Inter and intraassay CV were 8.2%, and 1.5%, respectively. Change in NEFA concentration was calculated as day 62 NEFA concentration − day 0 NEFA concentration, µmol/L.
Concentrations of BUN were measured in serum by using a coupled enzyme reaction, colorimetric assay urea N kit (Urea Assay Kit MAK0006, Sigma) at 570 nm absorbance following the manufacturer’s protocol. In brief, samples were compared with the standard curve after the average absorbance of the blank was subtracted from all samples and standards. The inter and intraassay CV were 12.1% and 4.7%, respectively. Change in BUN concentration was calculated as day 62 BUN concentration − day 0 BUN concentration, mM.
Histotroph analyses
Histotroph was analyzed for concentrations of AA and glucose using the aforementioned methods. Before AA analysis, each histotroph sample was concentrated 5× by freeze drying 2 mL of the histotroph flush and reconstituting it in 400 µL of PBS. Data were multiplied by 5 to correct for freeze drying. For glucose analysis, inter and intraassay CV were 4.5% and 2.9%, respectively.
Statistical analysis
Data were analyzed using the PROC GLM procedure of SAS 9.4 with a completely randomized design for fixed effects of plane of nutrition, replicate, and their interaction. Replicate and replicate × plane of nutrition were included in the model to account for changes of magnitude in cow BW across replicates but only the main effect of plane of nutrition is reported to satisfy the hypothesis. Any observed replicate × plane of nutrition interactions resulted primarily from magnitude and not differing treatment rankings. However, replicate and replicate × plane of nutrition were retained in the model. Cow was the experimental unit for all analyses. Data are reported as lsmeans ± standard error. The threshold for significance was P ≤ 0.05.
Results
Performance characteristics
There were no differences (P > 0.05) in cow age, initial BCS, initial BW, or final BW between treatment groups. However, final BCS, ADG, dry matter intake (DMI), and G:F were decreased (P ≤ 0.05) in NEG compared with CON cows (Table 1). Similarly, the changes in BCS and BW were greater (P ≤ 0.05) in NEG compared with CON cows (Table 1).
Table 1.
Age, body condition score (BCS), body weight (BW), average daily gain (ADG), dry matter intake (DMI), and gain:feed (G:F) in cows fed differing planes of nutrition for 62 d1
| Treatment2 | ||||
|---|---|---|---|---|
| CON | NEG | SE | P-value | |
| Cow age, yr | 6.20 | 6.20 | 1.00 | 0.97 |
| Initial BCS | 5.39 | 5.33 | 0.08 | 0.60 |
| Final BCS | 4.88 | 4.23 | 0.12 | <0.01 |
| BCS change | −0.51 | −1.10 | 0.13 | <0.01 |
| Initial BW, kg | 596.60 | 598.20 | 20.40 | 0.96 |
| Final BW, kg | 592.70 | 559.20 | 19.70 | 0.25 |
| BW change3, kg | −3.90 | −39.00 | 4.70 | <0.01 |
| ADG4, kg/d | −0.06 | −0.63 | 0.08 | <0.01 |
| DMI, kg DM/d | 7.62 | 5.82 | 0.27 | <0.01 |
| G:F5 | −0.01 | −0.11 | 0.01 | <0.01 |
1Data are presented as lsmeans ± standard error.
2CON = dietary intake designed to maintain weight (0.0 kg/d); NEG = dietary intake designed to lose moderate BW (-0.7 kg/d).
3BW change = final BW, kg − initial BW, kg.
4ADG = BW change, kg/62 d.
5BW change, kg / total feed intake DM, kg.
Body composition and carcass parameters
There were no differences (P > 0.05) in ultrasound body composition measures, including rump fat, rib fat, REA, or marbling, between treatment groups on day 0, 62, or in change in measures over the 62-d period (Table 2). Similarly, no differences (P > 0.05) were observed in HCW, backfat, REA, KPH fat, or YG between treatment groups on day 62 (Table 3). However, dressing percentage was increased (P = 0.02) in NEG compared with CON cows (Table 3).
Table 2.
Body composition traits assessed via ultrasonography in cows fed differing planes of nutrition for 62 d1
| Treatment2 | ||||
|---|---|---|---|---|
| Ultrasound measurement | CON | NEG | SE | P-value |
| Rump fat, cm | ||||
| Day 0 | 0.51 | 0.53 | 0.12 | 0.90 |
| Day 62 | 0.44 | 0.51 | 0.12 | 0.71 |
| Change3 | −0.07 | −0.03 | 0.03 | 0.28 |
| 12th Rib fat, cm | ||||
| Day 0 | 0.43 | 0.41 | 0.08 | 0.88 |
| Day 62 | 0.46 | 0.44 | 0.09 | 0.89 |
| Change3 | 0.02 | 0.02 | 0.03 | 0.99 |
| REA4, cm2 | ||||
| Day 0 | 72.75 | 76.46 | 3.52 | 0.47 |
| Day 62 | 76.20 | 78.75 | 2.73 | 0.52 |
| Change3 | 3.45 | 2.29 | 1.80 | 0.65 |
| 12th rib marbling, % | ||||
| Day 0 | 5.05 | 4.83 | 0.51 | 0.76 |
| Day 62 | 5.09 | 5.03 | 0.43 | 0.92 |
| Change3 | 0.04 | 0.20 | 0.22 | 0.61 |
1Data are presented as lsmeans ± standard error.
2CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
3Change = day 62 − day 0 measures.
4REA = ribeye area between the 12th and 13th rib.
Table 3.
Carcass characteristics in cows fed differing planes of nutrition for 62 d1
| Treatment2 | ||||
|---|---|---|---|---|
| Carcass characteristic | CON | NEG | SE | P-value |
| Hot carcass weight, kg | 312.60 | 310.90 | 12.40 | 0.93 |
| Dressing percent3, % | 52.60 | 55.50 | 0.80 | 0.02 |
| Backfat, mm | 5.52 | 3.56 | 1.26 | 0.29 |
| REA, cm2 | 83.73 | 83.31 | 2.82 | 0.92 |
| Kidney, pelvic, heart fat4, % | 1.70 | 1.60 | 0.10 | 0.31 |
| Yield Grade5 | 1.85 | 1.63 | 0.22 | 0.48 |
1Data are presented as lsmeans ± standard error.
2CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
3Dressing percent = hot carcass weight, kg/final live BW, kg.
4Evaluated subjectively as a percent of the HCW.
5Equation: 2.50 + (2.5 × backfat thickness, inches) + (0.2 × KPH, %) + (0.0038 × HCW, lbs)—(0.32 × REA, in.2).
Serum metabolites
There were no differences (P > 0.05) in serum NEFA concentrations on day 0 between treatment groups (Table 4). Serum NEFA concentrations on day 62 and the change in concentrations of NEFA from days 0 to 62 were greater (P ≤ 0.01) in NEG compared with CON cows (Table 4). There were no differences (P > 0.05) in serum glucose or BUN concentrations on day 0, 62, or in the change from days 0 to 62 between treatment groups (Table 4).
Table 4.
Serum non-esterified fatty acid (NEFA), glucose, and blood urea nitrogen (BUN) concentrations and changes in cows fed differing planes of nutrition for 62 d1
| Treatment2 | ||||
|---|---|---|---|---|
| Serum metabolite | CON | NEG | SE | P-value |
| NEFA, µmol/L | ||||
| Initial3 | 201.23 | 153.61 | 44.83 | 0.47 |
| Final4 | 307.20 | 645.33 | 83.32 | 0.01 |
| Change5 | 105.97 | 491.73 | 73.12 | <0.01 |
| Glucose, mg/dL | ||||
| Initial3 | 79.99 | 75.28 | 2.77 | 0.25 |
| Final4 | 82.35 | 78.24 | 4.27 | 0.51 |
| Change5 | 2.37 | 2.96 | 4.55 | 0.93 |
| BUN, mM | ||||
| Initial3 | 8.32 | 7.51 | 0.46 | 0.23 |
| Final4 | 6.95 | 7.52 | 0.47 | 0.40 |
| Change5 | -1.38 | 0.01 | 0.67 | 0.17 |
1Data are presented as lsmeans ± standard error.
2CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
3Day 0 concentrations.
4Day 62 concentrations.
5Change = day 62—day 0 concentration.
There were no differences (P > 0.05) in serum arginine, threonine, lysine, methionine, valine, leucine, or phenylalanine concentrations on day 62 between treatment groups (Table 5). However, serum histidine concentration was greater (P = 0.04) in NEG compared with control cows on day 62 (Table 5). Serum isoleucine and tryptophan were decreased (P < 0.05) in NEG vs. CON cows (Table 5). There were no differences (P > 0.05) in the change from days 0 to 62 in serum histidine, arginine, threonine, lysine, methionine, or phenylalanine concentrations between treatment groups (Table 5). For serum valine, isoleucine, and leucine concentrations, the change from days 0 to 62 was greater (P ≤ 0.05) in NEG compared with CON cows (Table 5).
Table 5.
Serum essential amino acid (AA) concentrations on day 62 and change1 in essential AA in cows fed differing planes of nutrition for 62 d2
| Treatment3 | ||||
|---|---|---|---|---|
| Essential AA | CON | NEG | SE | P-value |
| His | ||||
| Concentration, µmol/L | 61.56 | 71.63 | 3.14 | 0.04 |
| Change, µmol/L | 10.83 | 14.12 | 2.86 | 0.43 |
| Arg | ||||
| Concentration, µmol/L | 113.19 | 123.95 | 5.53 | 0.19 |
| Change, µmol/L | −17.54 | −10.36 | 7.05 | 0.48 |
| Thr | ||||
| Concentration, µmol/L | 64.89 | 64.48 | 4.36 | 0.95 |
| Change, µmol/L | −7.33 | −15.30 | 4.41 | 0.22 |
| Lys | ||||
| Concentration, µmol/L | 75.55 | 69.86 | 5.32 | 0.46 |
| Change, µmol/L | −8.95 | −23.28 | 5.58 | 0.09 |
| Met | ||||
| Concentration, µmol/L | 21.52 | 22.68 | 0.94 | 0.40 |
| Change, µmol/L | −0.90 | −2.88 | 1.05 | 0.21 |
| Val | ||||
| Concentration, µmol/L | 177.10 | 166.89 | 5.34 | 0.20 |
| Change, µmol/L | −16.93 | −58.39 | 7.32 | <0.01 |
| Ile | ||||
| Concentration, µmol/L | 82.85 | 74.82 | 2.54 | 0.04 |
| Change, µmol/L | −1.68 | −28.50 | 4.13 | <0.01 |
| Leu | ||||
| Concentration, µmol/L | 99.18 | 100.50 | 3.24 | 0.78 |
| Change, µmol/L | −6.02 | −24.70 | 4.78 | 0.02 |
| Phe | ||||
| Concentration, µmol/L | 47.87 | 47.33 | 1.77 | 0.83 |
| Change, µmol/L | −0.38 | −5.21 | 1.78 | 0.08 |
| Trp | ||||
| Concentration, µmol/L | 34.89 | 28.15 | 1.66 | 0.01 |
| Change, µmol/L | −1.66 | −9.84 | 2.44 | 0.03 |
1Change = AA final (day 62) concentration, µmol/L − AA initial (day 0) concentration, µmol/L.
2Data are presented as lsmeans ± standard error.
3CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
There were no differences (P > 0.05) in serum asparagine, serine, glutamine, glycine, aspartic acid, glutamic acid, proline, cysteine, or tyrosine concentrations on day 62 between treatment groups (Table 6). Serum alanine concentration was decreased (P = 0.02) in NEG compared with CON cows on day 62 (Table 6). For serum asparagine, serine, glutamine, glycine, aspartic acid, proline, and cysteine concentrations, there were no differences (P > 0.05) in the change from days 0 to 62 between treatment groups (Table 6). For serum glutamic acid, alanine, and tyrosine concentrations, the changes from days 0 to 62 were greater (P ≤ 0.05) in NEG compared with CON cows (Table 6).
Table 6.
Serum nonessential amino acid (AA) concentrations on day 62 and change1 in cows fed differing planes of nutrition for 62 d2
| Treatment3 | ||||
|---|---|---|---|---|
| Nonessential AA | CON | NEG | SE | P-Value |
| Asn | ||||
| Concentration, µmol/L | 49.97 | 42.23 | 2.77 | 0.07 |
| Change, µmol/L | 11.25 | −1.58 | 5.20 | 0.10 |
| Ser | ||||
| Concentration, µmol/L | 69.18 | 68.15 | 2.64 | 0.79 |
| Change, µmol/L | 3.83 | −0.13 | 4.78 | 0.57 |
| Gln | ||||
| Concentration, µmol/L | 334.71 | 364.39 | 17.59 | 0.25 |
| Change, µmol/L | 70.27 | 80.77 | 27.59 | 0.79 |
| Gly | ||||
| Concentration, µmol/L | 331.64 | 350.27 | 11.95 | 0.29 |
| Change, µmol/L | 73.51 | 74.81 | 18.33 | 0.96 |
| Asp | ||||
| Concentration, µmol/L | 10.67 | 9.56 | 0.52 | 0.16 |
| Change, µmol/L | −1.16 | −3.37 | 0.83 | 0.08 |
| Glu | ||||
| Concentration, µmol/L | 62.49 | 62.06 | 2.57 | 0.91 |
| Change, µmol/L | 4.571 | −8.49 | 3.60 | 0.02 |
| Ala | ||||
| Concentration, µmol/L | 181.81 | 160.56 | 5.69 | 0.02 |
| Change, µmol/L | −19.40 | −47.62 | 6.44 | <0.01 |
| Pro | ||||
| Concentration, µmol/L | 85.01 | 87.32 | 1.89 | 0.40 |
| Change, µmol/L | −3.22 | −5.60 | 2.86 | 0.56 |
| Cys | ||||
| Concentration, µmol/L | 2.29 | 2.03 | 0.11 | 0.12 |
| Change, µmol/L | −0.20 | −0.12 | 0.11 | 0.65 |
| Tyr | ||||
| Concentration, µmol/L | 31.87 | 31.61 | 1.64 | 0.91 |
| Change, µmol/L | −2.19 | −12.98 | 2.39 | <0.01 |
1AA change = AA final (day 62) concentration, µmol/L − AA initial (day 0) concentration, µmol/L.
2Data are presented as lsmeans ± standard error.
3CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
For serum arginine, threonine, lysine, methionine, valine, leucine, and phenylalanine concentrations, there were no differences (P > 0.05) as a proportion of total amino acid concentrations between treatment groups on day 62 (Table 7). Serum histidine concentration as a proportion of total amino acid concentration was increased (P ≤ 0.01) on day 62 in NEG compared with CON cows (Table 7). Serum tryptophan concentration as a proportion of total amino acid concentration was decreased (P = 0.01) on day 62 in NEG compared with CON cows (Table 7). For serum arginine, threonine, lysine, methionine, leucine, phenylalanine, and tryptophan concentrations, there were no differences (P > 0.05) in the change from day 0 to day 62 as a proportion of total amino acid concentration between treatment groups (Table 7). For serum histidine, valine, and isoleucine concentrations, the change from days 0 to 62 as a proportion of total amino acid concentration was greater (P ≤ 0.05) in NEG compared with CON cows (Table 7).
Table 7.
Serum essential amino acid (AA) as a proportion of total AA1 and change in AA proportion of total AA2 in cows fed differing planes of nutrition for 62 d3
| Treatment4 | ||||
|---|---|---|---|---|
| Essential amino acid | CON | NEG | SE | P-value |
| His | ||||
| Final5, % of total | 3.16 | 3.67 | 0.11 | <0.01 |
| Change in % of total | 0.43 | 0.84 | 0.09 | <0.01 |
| Arg | ||||
| Final5, % of total | 5.87 | 6.34 | 0.26 | 0.21 |
| Change in % of total | −1.15 | −0.26 | 0.29 | 0.05 |
| Thr | ||||
| Final5, % of total | 3.34 | 3.30 | 0.21 | 0.87 |
| Change in % of total | −0.54 | −0.60 | 0.14 | 0.78 |
| Lys | ||||
| Final5, % of total | 3.88 | 3.56 | 0.23 | 0.34 |
| Change in % of total | −0.62 | −1.01 | 0.20 | 0.11 |
| Met | ||||
| Final5, % of total | 1.11 | 1.16 | 0.04 | 0.44 |
| Change in % of total | −0.10 | −0.09 | 0.06 | 0.96 |
| Val | ||||
| Final5, % of total | 9.09 | 8.59 | 0.23 | 0.15 |
| Change in % of total | −1.36 | −2.46 | 0.32 | 0.03 |
| Ile | ||||
| Final5, % of total | 4.24 | 3.85 | 0.13 | 0.05 |
| Change in % of total | −0.30 | −1.22 | 0.15 | <0.01 |
| Leu | ||||
| Final5, % of total | 5.10 | 5.19 | 0.15 | 0.69 |
| Change in % of total | −0.55 | −0.95 | 0.22 | 0.22 |
| Phe | ||||
| Final5, % of total | 2.47 | 2.44 | 0.08 | 0.77 |
| Change in % of total | −0.12 | −0.16 | 0.08 | 0.73 |
| Trp | ||||
| Final5, % of total | 1.79 | 1.46 | 0.08 | 0.01 |
| Change in % of total | −0.17 | −0.40 | 0.10 | 0.12 |
1AA proportion of total AA = (AA final (day 62) concentration, µmol/L/total final (day 62) AA concentration, µmol/L) * 100.
2AA change in % of total = [(AA final (day 62) concentration, µmol/L/total final (day 62) AA concentration, µmol/L) * 100] – [(AA initial (day 0) concentration, µmol/L/total initial (day 0) AA concentration, µmol/L) * 100].
3Data are presented as lsmeans ± standard error.
4CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (-0.7 kg/d).
5Concentrations on day 62.
There were no differences (P > 0.05) between treatment groups in serum serine, glutamine, glycine, asparagine, glutamic acid, proline, cysteine, or tyrosine concentrations as a proportion of total amino acid concentration on day 62 (Table 8). Serum asparagine and alanine concentrations as a proportion of total amino acid concentration were decreased (P ≤ 0.05) on day 62 in NEG compared with CON cows (Table 8). For serum asparagine, serine, glutamine, glycine, aspartic acid, glutamic acid, alanine, proline, and cysteine concentrations, there were no differences (P > 0.05) in the change from days 0 to 62 as a proportion of total amino acid concentration (Table 8). For serum tyrosine concentration, the change from days 0 to 62 as a proportion of total amino acid concentration was greater (P = 0.01) in NEG compared with CON cows (Table 8).
Table 8.
Serum nonessential amino acids (AA) as a proportion of total AA1 and change in AA proportion of total AA2 in cows fed differing planes of nutrition for 62 d3
| Treatment4 | ||||
|---|---|---|---|---|
| Nonessential Amino Acid | CON | NEG | SE | P-value |
| Asn | ||||
| Final5, % of total | 2.52 | 2.13 | 0.11 | 0.02 |
| Change in % of total | 0.46 | 0.00 | 0.19 | 0.11 |
| Ser | ||||
| Final5, % of total | 3.60 | 3.52 | 0.11 | 0.64 |
| Change in % of total | 0.07 | 0.18 | 0.17 | 0.66 |
| Gln | ||||
| Final5, % of total | 17.76 | 18.49 | 0.60 | 0.14 |
| Change in % of total | 2.86 | 4.72 | 0.92 | 0.17 |
| Gly | ||||
| Final5, % of total | 17.24 | 18.05 | 0.53 | 0.29 |
| Change in % of total | 3.10 | 4.36 | 1.01 | 0.39 |
| Asp | ||||
| Final5, % of total | 0.55 | 0.50 | 0.02 | 0.11 |
| Change in % of total | −0.09 | −0.14 | 0.03 | 0.35 |
| Glu | ||||
| Final5, % of total | 3.26 | 3.21 | 0.14 | 0.80 |
| Change in % of total | 0.10 | −0.25 | 0.19 | 0.20 |
| Ala | ||||
| Final5, % of total | 9.44 | 8.30 | 0.31 | 0.02 |
| Change in % of total | −1.47 | −1.92 | 0.33 | 0.34 |
| Pro | ||||
| Final5, % of total | 4.43 | 4.52 | 0.11 | 0.58 |
| Change in % of total | −0.36 | −0.07 | 0.16 | 0.22 |
| Cys | ||||
| Final5, % of total | 0.12 | 0.11 | 0.01 | 0.16 |
| Change in % of total | −0.02 | 0.00 | 0.01 | 0.17 |
| Tyr | ||||
| Final5, % of total | 1.64 | 1.62 | 0.08 | 0.82 |
| Change in % of total | −0.19 | −0.57 | 0.10 | 0.01 |
1AA proportion of total AA = (AA final (day 62) concentration, µmol/L/total final (day 62) AA concentration, µmol/L) * 100.
2AA change in % of total = [(AA final (day 62) concentration, µmol/L/total final (day 62) AA concentration, µmol/L) * 100] – [(AA initial (day 0) concentration, µmol/L/total initial (day 0) AA concentration, µmol/L) * 100].
3Data are presented as lsmeans ± standard error.
4CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
5Concentrations on day 62.
There were no differences (P > 0.05) in serum total essential amino acids, total nonessential amino acids, or total amino acid concentrations on day 62 between treatment groups (Table 9). There were no differences (P > 0.05) between treatment groups in the change from days 0 to 62 in serum nonessential amino acid concentration or total amino acid concentration (Table 9). The change in serum essential amino acid concentrations from day 0 to 62 was greater (P = 0.04) in NEG cows compared with CON cows (Table 9). There was no difference (P > 0.05) between treatment groups in the change from days 0 to 62 for serum total essential or total nonessential amino acid concentrations as a proportion of total amino acids (Table 9).
Table 9.
Serum total essential and nonessential amino acid (AA) concentrations and total AA on d 62 in cows fed differing planes of nutrition for 62 d1
| Treatment2 | ||||
|---|---|---|---|---|
| Item | CON | NEG | SE | P-value |
| Total Essential AA | ||||
| Concentration, µmol/L | 778.60 | 770.29 | 24.21 | 0.81 |
| Change3, µmol/L | -50.55 | −164.32 | 34.64 | 0.04 |
| Final4, % of total | 40.05 | 39.56 | 0.85 | 0.69 |
| Change in % of total | −4.47 | −6.31 | 1.06 | 0.24 |
| Total Non-Essential AA | ||||
| Concentration, µmol/L | 1159.63 | 1178.19 | 32.70 | 0.69 |
| Change, µmol/L | 137.26 | 75.68 | 50.63 | 0.40 |
| Final, % of total | 59.95 | 60.45 | 0.85 | 0.69 |
| Change in % of total | 4.47 | 6.31 | 1.06 | 0.24 |
| Total AA | ||||
| Concentration, µmol/L | 1,938.23 | 1,948.48 | 46.46 | 0.88 |
| Change, µmol/L | 86.70 | −88.64 | 72.84 | 0.11 |
1Data are presented as lsmeans ± standard error.
2AA change = AA final (d 62) concentration, µmol/L—AA initial (d 0) concentration, µmol/L.
2AA proportion of total AA = (AA final (d 62) concentration, µmol/L / total final (d 62) AA concentration, µmol/L) *100.
3AA change in % of total = [(AA final (day 62) concentration, µmol/L/total final (d 62) AA concentration, µmol/L) *100] – [(AA initial (day 0) concentration, µmol/L/total initial (day 0) AA concentration, µmol/L) *100].
4Total AA change = final (day 62) total AA concentration, µmol/L – initial (day 0) total AA concentration, µmol/L.
5CON = dietary intake designed to maintain weight; NEG = dietary intake designed to lose weight at a moderate rate (−0.7 kg/d).
6Concentrations on day 62.
Histotroph composition
In histotroph ipsilateral to the CL, there were no differences (P > 0.05) between treatment groups in concentrations of histidine, arginine, threonine, lysine, methionine, valine, isoleucine, leucine, phenylalanine, or tryptophan, or of any of these amino acids as a proportion of essential or total amino acid concentrations (Table 10). In histotroph ipsilateral to the CL, there were no differences (P > 0.05) between treatment groups in concentrations of asparagine, serine, glutamine, glycine, aspartic acid, glutamic acid, alanine, proline, cysteine, or tyrosine, or any of these as a proportion of nonessential amino acid concentrations (Table 11). In histotroph ipsilateral to the CL, there were no differences (P > 0.05) in asparagine, glutamine, glycine, aspartic acid, glutamic acid, alanine, proline, cysteine, or tyrosine concentrations as a proportion of total amino acid concentration (Table 11). In contrast, serine concentration as a proportion of total amino acid concentration was decreased (P = 0.05) in histotroph ipsilateral to the CL in NEG compared with CON cows (Table 11).
Table 10.
Histotroph ipsilateral to the CL essential amino acid (AA) concentrations on day 62, proportion of essential AA concentration1, and proportion of total AA concentration2 in cows fed differing planes of nutrition for 62 d3
| Treatment4 | ||||
|---|---|---|---|---|
| Essential AA | CON | NEG | SE | P-value |
| His | ||||
| Concentration, µmol/L | 4.58 | 3.34 | 1.32 | 0.51 |
| % of essential AA | 9.15 | 7.71 | 0.92 | 0.27 |
| % of total AA | 1.88 | 1.46 | 0.22 | 0.19 |
| Arg | ||||
| Concentration, µmol/L | 6.26 | 5.91 | 1.09 | 0.82 |
| % of essential AA | 13.93 | 13.95 | 0.55 | 0.98 |
| % of total AA | 2.83 | 2.66 | 0.21 | 0.55 |
| Thr | ||||
| Concentration, µmol/L | 8.45 | 7.55 | 1.68 | 0.71 |
| % of essential AA | 18.03 | 17.78 | 0.72 | 0.80 |
| % of total AA | 3.82 | 3.38 | 0.21 | 0.15 |
| Lys | ||||
| Concentration, µmol/L | 2.04 | 2.75 | 0.37 | 0.20 |
| % of essential AA | 5.66 | 6.74 | 0.70 | 0.28 |
| % of total AA | 1.17 | 1.28 | 0.16 | 0.62 |
| Met | ||||
| Concentration, µmol/L | 2.04 | 1.81 | 0.46 | 0.73 |
| % of essential AA | 4.32 | 4.24 | 0.14 | 0.70 |
| % of total AA | 0.88 | 0.81 | 0.04 | 0.19 |
| Val | ||||
| Concentration, µmol/L | 6.23 | 6.41 | 1.01 | 0.91 |
| % of essential AA | 14.66 | 15.58 | 0.47 | 0.17 |
| % of total AA | 2.95 | 2.96 | 0.12 | 0.96 |
| Ile | ||||
| Concentration, µmol/L | 3.25 | 3.36 | 0.54 | 0.89 |
| % of essential AA | 7.68 | 8.06 | 0.24 | 0.25 |
| % of total AA | 1.57 | 1.53 | 0.07 | 0.71 |
| Leu | ||||
| Concentration, µmol/L | 5.77 | 6.06 | 0.96 | 0.83 |
| % of essential AA | 13.57 | 14.71 | 0.46 | 0.09 |
| % of total AA | 2.77 | 2.79 | 0.13 | 0.91 |
| Phe | ||||
| Concentration, µmol/L | 5.84 | 4.00 | 1.91 | 0.49 |
| % of essential AA | 9.79 | 8.64 | 0.68 | 0.23 |
| % of total AA | 2.00 | 1.64 | 0.19 | 0.17 |
| Trp | ||||
| Concentration, µmol/L | 1.90 | 1.18 | 0.59 | 0.39 |
| % of essential AA | 3.22 | 2.59 | 0.30 | 0.15 |
| % of total AA | 0.62 | 0.49 | 0.06 | 0.14 |
1AA proportion of essential AA = (AA concentration, µmol/L/total essential AA concentration, µmol/L) *100.
2AA proportion of total AA = (AA concentration, µmol/L/total AA concentration, µmol/L) *100.
3Data are presented as lsmeans ± standard error.
4CON = dietary intake designed to maintain weight; NEG = dietary intake designed to lose weight at a moderate rate (−0.7 kg/d).
Table 11.
Histotroph ipsilateral to the CL nonessential amino acid (AA) concentrations on d 62, proportion of nonessential AA concentration1, and proportion of total AA concentration2 in cows fed differing planes of nutrition for 62 d3
| Treatment4 | ||||
|---|---|---|---|---|
| Nonessential AA | CON | NEG | SE | P-value |
| Asn | ||||
| Concentration, µmol/L | 4.26 | 3.54 | 0.97 | 0.61 |
| % of nonessential AA | 2.31 | 2.06 | 0.16 | 0.25 |
| % of total AA | 1.83 | 1.57 | 0.10 | 0.08 |
| Ser | ||||
| Concentration, µmol/L | 13.37 | 9.06 | 3.45 | 0.39 |
| % of nonessential AA | 7.46 | 5.25 | 0.91 | 0.08 |
| % of total AA | 5.91 | 3.96 | 0.67 | 0.05 |
| Gln | ||||
| Concentration, µmol/L | 30.52 | 28.52 | 6.16 | 0.82 |
| % of nonessential AA | 15.94 | 16.64 | 1.18 | 0.64 |
| % of total AA | 12.65 | 12.67 | 0.71 | 0.98 |
| Gly | ||||
| Concentration, µmol/L | 67.27 | 68.60 | 13.80 | 0.95 |
| % of nonessential AA | 37.44 | 39.11 | 0.99 | 0.20 |
| % of total AA | 29.77 | 31.85 | 0.92 | 0.12 |
| Asp | ||||
| Concentration, µmol/L | 4.17 | 4.93 | 0.82 | 0.52 |
| % of nonessential AA | 2.57 | 2.79 | 0.19 | 0.38 |
| % of total AA | 2.05 | 2.28 | 0.16 | 0.31 |
| Glu | ||||
| Concentration, µmol/L | 28.77 | 35.09 | 4.51 | 0.34 |
| % of nonessential AA | 18.84 | 19.72 | 2.00 | 0.73 |
| % of total AA | 15.03 | 16.92 | 1.68 | 0.41 |
| Ala | ||||
| Concentration, µmol/L | 17.43 | 16.96 | 2.56 | 0.90 |
| % of nonessential AA | 10.12 | 9.58 | 0.43 | 0.33 |
| % of total AA | 8.04 | 7.83 | 0.36 | 0.66 |
| Pro | ||||
| Concentration, µmol/L | 5.38 | 5.93 | 1.00 | 0.71 |
| % of nonessential AA | 3.17 | 3.31 | 0.25 | 0.65 |
| % of total AA | 2.51 | 2.67 | 0.20 | 0.58 |
| Cys | ||||
| Concentration, µmol/L | 0.66 | 0.61 | 0.17 | 0.85 |
| % of nonessential AA | 0.32 | 0.36 | 0.09 | 0.75 |
| % of total AA | 0.26 | 0.28 | 0.08 | 0.84 |
| Tyr | ||||
| Concentration, µmol/L | 5.17 | 2.17 | 1.94 | 0.24 |
| % of nonessential AA | 1.84 | 1.18 | 0.30 | 0.11 |
| % of total AA | 1.46 | 1.00 | 0.25 | 0.19 |
1AA proportion of nonessential AA = (AA concentration, µmol/L/total nonessential AA concentration, µmol/L) * 100.
2AA proportion of total AA = (AA concentration, µmol/L/total AA concentration, µmol/L) * 100.
3Data are presented as lsmeans ± standard error.
4CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
In histotroph contralateral to the CL, there were no differences (P > 0.05) between treatment groups in histidine, arginine, threonine, methionine, valine, leucine, phenylalanine, or tryptophan concentrations, or any of these as a proportion of total amino acid concentration (Table 12). Concentrations of lysine and isoleucine in histotroph contralateral to the CL were increased (P ≤ 0.05) in NEG compared with CON cows, but as proportions of essential or total amino acid concentrations they were not different (P > 0.05; Table 12). Tryptophan concentration in histotroph contralateral to the CL was decreased (P ≤ 0.01) as a proportion of essential amino acid concentration in NEG compared with CON cows (Table 12). Asparagine, serine, glutamine, glycine, glutamic acid, alanine, cysteine, and tyrosine concentrations did not differ (P > 0.05) between treatment groups in histotroph contralateral to the CL (Table 13). However, aspartic acid and proline concentrations in histotroph contralateral to the CL were increased (P ≤ 0.05) in NEG compared with CON cows (Table 13). There were no differences (P > 0.05) in asparagine, serine, glutamine, glycine, aspartic acid, glutamic acid, alanine, proline, or tyrosine concentrations as a proportion of nonessential or total amino acid concentrations in histotroph contralateral to the CL (Table 13). In contrast, cysteine concentration as a proportion of nonessential and total amino acid concentrations was decreased (P ≤ 0.05) in histotroph contralateral to the CL in NEG compared with CON cows (Table 13).
Table 12.
Histotroph contralateral to the CL essential amino acid (AA) concentrations on d 62, proportion of essential AA concentration1, and proportion of total AA concentration2 in cows fed differing planes of nutrition for 62 d3
| Treatment4 | ||||
|---|---|---|---|---|
| Essential AA | CON | NEG | SE | P-value |
| His | ||||
| Concentration, µmol/L | 2.70 | 3.53 | 0.36 | 0.13 |
| % of essential AA | 8.55 | 7.92 | 0.48 | 0.29 |
| % of total AA | 1.68 | 1.55 | 0.15 | 0.49 |
| Arg | ||||
| Concentration, µmol/L | 4.64 | 6.18 | 0.62 | 0.10 |
| % of essential AA | 14.36 | 14.13 | 0.60 | 0.75 |
| % of total AA | 2.81 | 2.76 | 0.23 | 0.85 |
| Thr | ||||
| Concentration, µmol/L | 5.97 | 7.88 | 0.77 | 0.10 |
| % of essential AA | 18.42 | 18.19 | 1.20 | 0.87 |
| % of total AA | 3.59 | 3.55 | 0.28 | 0.89 |
| Lys | ||||
| Concentration, µmol/L | 1.74 | 2.55 | 0.27 | 0.05 |
| % of essential AA | 5.23 | 6.33 | 0.74 | 0.24 |
| % of total AA | 1.03 | 1.22 | 0.15 | 0.31 |
| Met | ||||
| Concentration, µmol/L | 1.80 | 2.42 | 0.27 | 0.13 |
| % of essential AA | 4.63 | 5.49 | 1.29 | 0.59 |
| % of total AA | 0.90 | 1.07 | 0.24 | 0.58 |
| Val | ||||
| Concentration, µmol/L | 4.74 | 6.31 | 0.59 | 0.08 |
| % of essential AA | 14.88 | 14.81 | 0.60 | 0.93 |
| % of total AA | 2.92 | 2.87 | 0.26 | 0.87 |
| Ile | ||||
| Concentration, µmol/L | 2.40 | 3.30 | 0.30 | 0.05 |
| % of essential AA | 7.48 | 7.75 | 0.30 | 0.46 |
| % of total AA | 1.47 | 1.50 | 0.12 | 0.80 |
| Leu | ||||
| Concentration, µmol/L | 4.33 | 5.96 | 0.55 | 0.06 |
| % of essential AA | 13.66 | 13.96 | 0.45 | 0.59 |
| % of total AA | 2.68 | 2.71 | 0.20 | 0.90 |
| Phe | ||||
| Concentration, µmol/L | 3.70 | 4.05 | 0.58 | 0.62 |
| % of essential AA | 9.63 | 8.86 | 0.41 | 0.15 |
| % of total AA | 1.89 | 1.73 | 0.14 | 0.38 |
| Trp | ||||
| Concentration, µmol/L | 1.21 | 1.17 | 0.15 | 0.81 |
| % of essential AA | 3.17 | 2.57 | 0.13 | <0.01 |
| % of total AA | 0.63 | 0.50 | 0.06 | 0.10 |
1AA proportion of essential AA = (AA concentration, µmol/L/total essential AA concentration, µmol/L) * 100.
2AA proportion of total AA = (AA concentration, µmol/L/total AA concentration, µmol/L) * 100.
3Data are presented as lsmeans ± standard error.
4CON = dietary intake designed to maintain weight; NEG = dietary intake designed to lose weight at a moderate rate (−0.7 kg/d).
Table 13.
Histotroph contralateral to the CL nonessential amino acid (AA) concentrations on day 62, proportion of nonessential AA concentration1, and proportion of total AA concentration2 in cows fed differing planes of nutrition for 62 d3
| Treatment4 | ||||
|---|---|---|---|---|
| Nonessential Amino Acids | CON | NEG | SE | P-value |
| Asn | ||||
| Concentration, µmol/L | 2.99 | 3.77 | 0.36 | 0.15 |
| % of nonessential AA | 2.23 | 2.08 | 0.10 | 0.30 |
| % of total AA | 1.91 | 1.67 | 0.08 | 0.04 |
| Ser | ||||
| Concentration, µmol/L | 7.64 | 9.40 | 0.91 | 0.19 |
| % of nonessential AA | 5.54 | 5.13 | 0.36 | 0.42 |
| % of total AA | 4.18 | 4.12 | 0.38 | 0.91 |
| Gln | ||||
| Concentration, µmol/L | 22.64 | 29.94 | 2.60 | 0.07 |
| % of nonessential AA | 16.30 | 16.64 | 0.81 | 0.76 |
| % of total AA | 13.51 | 13.39 | 1.02 | 0.92 |
| Gly | ||||
| Concentration, µmol/L | 51.64 | 70.46 | 6.88 | 0.07 |
| % of nonessential AA | 38.38 | 39.09 | 1.47 | 0.73 |
| % of total AA | 30.48 | 31.47 | 1.95 | 0.68 |
| Asp | ||||
| Concentration, µmol/L | 3.18 | 4.70 | 0.43 | 0.03 |
| % of nonessential AA | 2.40 | 2.73 | 0.19 | 0.19 |
| % of total AA | 2.00 | 2.20 | 0.24 | 0.50 |
| Glu | ||||
| Concentration, µmol/L | 24.69 | 34.83 | 3.50 | 0.06 |
| % of nonessential AA | 19.61 | 20.22 | 1.58 | 0.78 |
| % of total AA | 16.11 | 16.32 | 1.92 | 0.93 |
| Ala | ||||
| Concentration, µmol/L | 14.28 | 16.90 | 1.38 | 0.20 |
| % of nonessential AA | 10.85 | 9.63 | 0.45 | 0.07 |
| % of total AA | 8.41 | 7.76 | 0.48 | 0.29 |
| Pro | ||||
| Concentration, µmol/L | 4.15 | 6.02 | 0.56 | 0.03 |
| % of nonessential AA | 3.19 | 3.40 | 0.19 | 0.43 |
| % of total AA | 2.45 | 2.74 | 0.22 | 0.29 |
| Cys | ||||
| Concentration, µmol/L | 0.61 | 0.40 | 0.10 | 0.16 |
| % of nonessential AA | 0.41 | 0.21 | 0.05 | 0.01 |
| % of total AA | 0.34 | 0.17 | 0.07 | 0.05 |
| Tyr | ||||
| Concentration, µmol/L | 1.67 | 1.75 | 0.35 | 0.88 |
| % of nonessential AA | 1.13 | 0.88 | 0.17 | 0.29 |
| % of total AA | 1.02 | 0.70 | 0.18 | 0.17 |
1AA proportion of nonessential AA = (AA concentration, µmol/L/total nonessential AA concentration, µmol/L) * 100.
2AA proportion of total AA = (AA concentration, µmol/L/total AA concentration, µmol/L) * 100.
3Data are presented as lsmeans ± standard error.
4CON = dietary intake designed to maintain weight; NEG = dietary intake designed to lose weight at a moderate rate (−0.7 kg/d).
There were no differences (P > 0.05) between treatment groups for concentrations of essential, nonessential, or either of these as a proportion of total amino acid concentrations in histotroph ipsilateral or contralateral to the CL (Table 14). Similarly, there were no differences (P > 0.05) between treatment groups for concentrations of glucose in histotroph ipsilateral to the CL (CON: 1.57 ± 0.20 mg/dL vs. NEG: 1.44 ± 0.20 mg/dL) or contralateral to the CL (CON: 1.23 ± 0.16 mg/dL vs. NEG: 1.64 ± 0.16 mg/dL).
Table 14.
Ipsilateral and contralateral to the CL total essential, total nonessential, and total amino acid (AA) concentrations and percentage of total AA concentrations1 in histotroph of cows fed differing planes of nutrition for 62 d2
| Treatment3 | ||||
|---|---|---|---|---|
| Item | CON | NEG | SE | P-value |
| Ipsilateral | ||||
| Total essential AA | ||||
| Concentration, µmol/L | 53.89 | 46.39 | 12.12 | 0.65 |
| % of total AA | 20.51 | 19.01 | 0.91 | 0.24 |
| Total nonessential AA | ||||
| Concentration, µmol/L | 222.59 | 175.42 | 46.05 | 0.43 |
| % of total AA | 79.49 | 80.99 | 0.91 | 0.24 |
| Total AA | ||||
| Concentration, µmol/L | 280.12 | 242.15 | 60.80 | 0.64 |
| Contralateral | ||||
| Total essential AA | ||||
| Concentration, µmol/L | 38.26 | 45.14 | 5.27 | 0.30 |
| % of total AA | 19.60 | 19.46 | 1.21 | 0.92 |
| Total nonessential AA | ||||
| Concentration, µmol/L | 148.28 | 186.27 | 14.87 | 0.09 |
| % of total AA | 80.41 | 80.55 | 1.21 | 0.92 |
| Total AA | ||||
| Concentration, µmol/L | 197.26 | 231.41 | 27.52 | 0.32 |
1AA proportion of total AA = (AA concentration, µmol/L/total AA concentration, µmol/L) * 100.
2Data are presented as lsmeans ± standard error.
3CON = dietary intake designed to maintain BW (0 kg/d); NEG = dietary intake designed to lose moderate BW (−0.7 kg/d).
Discussion
This model utilized differing planes of nutrition, maintain BW or moderate loss, to evaluate the nutrient composition of serum and histotroph in multiparous beef cows during instances of decreased nutrient availability as a model for postpartum negative energy balance. This model was successful, shown by reduced BCS and a greater change in BW observed in the NEG group. Furthermore, NEFA concentrations were elevated in NEG group serum, indicating the mobilization of fatty acids from adipose stores, which is often seen in ruminants during periods of limited nutrient availability (Vonnahme et al., 2013). More importantly, this study reports plane of nutrition alters histotroph amino acid composition in beef cows, interestingly more so in the contralateral horn. These results will fill critical gaps in our current understanding of factors affecting histotroph nutrient composition at the time an embryo would be entering the uterus, which is critical for early embryonic growth, development, and survival.
This moderate BW loss model was selected because it mirrors natural BW fluctuations among cows during periods of reduced forage availability, and forage quality in summer and winter months and postpartum negative energy balance (Laurenz et al., 1992; Caton and Dhuyvetter, 1997; NASEM, 2016; Ag Guide, 2020). Maintaining herd BW during these periods requires supplementation, which is often challenging to provide due to financial and labor constraints (Caton and Dhuyvetter, 1997). Similarly, cows undergo a period of negative energy balance following parturition, which negatively impacts return to cyclicity and first service pregnancy rates (Wiltbank et al., 1962). Interestingly, the present study is 62 d, aligning with the period in which cows need to resume cyclicity to maintain a 12-mo calving interval (Wiltbank et al., 1962; Perkins and Kidder, 1963). Perhaps, one factor influencing postpartum conception is altered histotroph nutrient composition due to a negative energy balance, demonstrated in the present study.
In the present study, alterations in NEG cow serum amino acids is in agreeance with previous work in nutrient restricted early and late gestation beef cows and late gestation sheep (Lemley et al., 2013; Crouse et al., 2019; Swanson et al., 2022). Reduction in serum histidine in NEG cows is notable not only because of the role of histidine as an essential amino acid but also its bioactive roles in the immune system, specifically anti-oxidant capacity and the cascade for pro-inflammatory histamine (Coleman et al., 2020). The early pregnancy uterine inflammatory response is important throughout pregnancy and in offspring postnatal growth and health (Bromfield, 2014). Less histidine may reduce histamine, and thus disrupt the necessary early gestation immune response during its most critical period. Similarly, tryptophan’s role expands beyond an essential amino as it is the precursor for serotonin and further downstream, melatonin. Interestingly, nutrient restricted late-gestation pregnant heifers had increased serotonin and serotonin receptors, and maternal plasma serotonin was correlated with cotyledonary serotonin concentrations (Harman et al., 2023). While this aforementioned study is in late-gestation cows, early perturbations in tryptophan during the period pre-implantation period may have lasting effects. Isoleucine is a branched-chain essential amino acid with broad impacts in skeletal muscle and liver metabolism, glucose homeostasis, and immune function (Zhang et al., 2017). Isoleucine reductions in NEG cows is likely because of the shifts in metabolic function occurring in the absence of adequate nutrients, which may be consequential for pregnancy maintenance.
In histotroph contralateral to the CL, lysine and isoleucine concentrations were increased in NEG cows, while tryptophan concentration as a proportion of essential and total amino acid concentrations were decreased. These data agree with previous work showing altered amino acids in fetal fluids in nutrient restricted primiparous beef cows during early and late gestation (Crouse et al., 2019; Swanson et al., 2022). The importance of amino acids in conceptus growth and development has been previously demonstrated (Mullen et al., 2012; Artus et al., 2020). Moreover, tryptophan is not only an essential amino acid necessary for protein synthesis but it also has significant bioactive affects such as vasodilation, immune function, gut motility, kynurenine, serotonin and melatonin synthesis, and gut-brain axis homeostasis (Roth et al., 2021). Programmed alterations in a developing embryo or fetuses in any of these aforementioned biologic activities could alter offspring growth and development, as well as health and well-being.
Overall, differing planes of nutrition alter serum and contralateral histotroph amino acid composition which may impact the uterine environment as it prepares for entrance of the embryo. Future studies are needed to fully elucidate alterations of histotroph composition. Concentrations and bioactivity of histidine, tryptophan, and isoleucine may be of special interest in future work, specifically in the presence of an embryo.
Acknowledgment
This manuscript is based on research that was supported by the North Dakota Agriculture Experiment Station. Mention of a trade name, proprietary product, or specific agreement does not constitute a guarantee or warranty by the USDA and does not imply approval to the inclusion of other products that may be suitable. USDA is an equal opportunity provider and employer.
Glossary
Abbreviations
- AA
amino acid
- ADG
average daily gain
- BCS
body condition score
- BUN
blood urea nitrogen
- BW
body weight
- CIDR
controlled internal drug release device
- CL
corpus luteum
- DMI
dry matter intake
- G:F
gain:feed
- GnRH
gonadotropin releasing hormone
- HCW
hot carcass weight
- KPH
kidney, pelvic, heart fat
- NEFA
non-esterified fatty acids
- REA
ribeye area
- UPLC
ultra-performance liquid chromatograph
- YG
yield grade
Contributor Information
Rebecca M Swanson, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Tammi L Neville, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Kacie L McCarthy, Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 68583, USA.
Cierrah J Kassetas, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Pawel P Borowicz, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Matthew S Crouse, USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933, USA.
Lawrence P Reynolds, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Carl R Dahlen, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Joel S Caton, Center for Nutrition and Pregnancy, Department of Animal Sciences, North Dakota State University, Fargo, ND 58108, USA.
Conflict of interest statement
The authors declare no real or perceived conflicts of interest.
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