Supplemental trace minerals as complexed or inorganic sources for beef cattle during the receiving period

Abstract

To investigate effects of inorganic or complexed trace mineral source (zinc, copper, manganese, and cobalt) on receiving period performance and morbidity, crossbred beef heifer calves (n = 287) arriving on three delivery dates were used in a 42-d receiving trial. Heifers were processed after arrival, stratified by day −1 body weights (BW) and allocated randomly to eight pens (11 to 13 heifers/pen, 24 pens total). Within truckload, pens were assigned randomly to dietary treatment (n = 12 pens/treatment). Heifers were housed on 0.42-ha grass paddocks, provided ad libitum bermudagrass hay and provided dietary treatments in grain supplements fed daily. Treatments consisted of supplemental zinc (360 mg/d), copper (125 mg/d), manganese (200 mg/d), and cobalt (12 mg/d) from complexed (Zinpro Availa 4, Zinpro Corp. Eden Prairie, MN) or inorganic sources (sulfates). Heifers were observed daily for clinical bovine respiratory disease (BRD). If presenting BRD symptoms and rectal temperature ≥ 40 °C, heifers were deemed morbid and treated with antibiotics. Six heifers/pen were bled to determine serum haptoglobin concentrations on days 0, 14, and 28. Liver biopsies were taken on day 5 ± 2 and 43 ± 1 from three calves selected randomly from each pen for mineral status comparisons. Statistical analyses were performed using the MIXED, GLIMMIX, and repeated measures procedures of SAS 9.4 with truckload as a random effect and pen within truckload specified as subject. There tended to be a treatment by day interaction for BW (P = 0.07). Heifer BW did not differ on day 0 (P = 0.82) and day 14 (P = 0.36), but heifers fed complexed trace minerals had greater BW on day 28 (P = 0.04) and day 42 (P = 0.05). Overall average daily gains were greater for heifers fed complexed trace minerals (P = 0.05; 0.78 vs. 0.70 kg, SE = 0.03). Heifers supplemented with inorganic trace minerals had greater BRD incidence (P = 0.03; 58 vs. 46%, SE = 3.6). Haptoglobin concentrations decreased throughout the trial (P < 0.001), and heifers fed complexed trace minerals tended to have a decrease in haptoglobin concentrations (P = 0.07). The source of trace mineral supplementation had no effect (P ≥ 0.20) on liver mineral concentrations and there were no treatment × day interactions (P ≥ 0.35). In conclusion, supplementing diets for the first 42 d after arrival with complexed trace mineral sources improved heifer performance as compared to heifers supplemented with inorganic trace minerals.

Supplementing cattle for the first 42 d after arrival with complexed trace mineral sources improved heifer growth performance and overall health as compared to heifers supplemented with inorganic trace minerals.

Introduction

Trace minerals have important physiological functions in beef cattle and must be supplemented to beef cattle diets when forages and rations are deficient or have incorrect proportions (Paterson and Engle, 2005). Mineral inclusion to livestock diets must be sufficient to ensure the maintenance of body reserves and in turn provide appropriate concentrations in products that are palatable. Various sources, concentrations, and combinations of trace mineral supplements exist commercially for cattle. The effects of trace mineral sources on immune function, growth, and performance measures have been evaluated in recent years. Livestock diets are often delivered with trace minerals supplemented in the form of inorganic salts, usually oxides, chlorides, sulfates, and carbonates (Hilal et al., 2016). These inorganic forms have been used in cattle diets for years because they are widely available and represent an inexpensive form of supplementation. However, organic trace mineral supplements are now being used in replacement of inorganic salts due to potentially greater bioavailability and functionality (Mohanta and Garg, 2014). There are different forms of organic trace mineral supplementation commercially available. Furthermore, updated literature is needed to investigate or validate the effects of mineral source inclusion in cattle diets. The metal amino acid complex, used in this study, results from complexing a soluble metal salt with a single amino acid (AAFCO, 2000).

Issues associated with health and management of newly received cattle continue to pose significant animal welfare and economical challenges for the beef industry. Bovine respiratory disease (BRD) has been the most economically important disease costing producers in North America $800 to $900 million every year (Sanchez, 2022). Such loss remains a continuing problem in cattle production systems despite the widespread use of antibiotics and vaccines (Ellis, 2001). Morbidity accompanied with poor growth performance in receiving cattle has long been addressed by nutritional intervention. Thus, the objective of this experiment is to investigate the effects of inorganic or complexed sources of trace minerals (zinc, copper, manganese, and cobalt) on beef heifer growth performance, morbidity, and mineral status during a receiving period.

Materials and Methods

Animal methods were approved by the University of Arkansas Animal Care and Use Committee (Approval #21142).

Two hundred eighty-seven crossbred beef heifers (231 ± 0.49 kg) were obtained from a cooperating producer, who purchased calves in small groups in regional sale barns (within 250 km) over a period of 3 d, transporting them to a single site. Then cattle were shipped (150 km) to the University of Arkansas Division of Agriculture Beef Cattle Research Facility near Fayetteville, AR. Heifers arrived in 3 shipment sets (block) with arrival dates of October 6, 2021 (block 1, n = 94, 232 ± 2 kg), October 26, 2021 (block 2, n = 95, 230 ± 2 kg), and November 23, 2021 (block 3, n = 98, 230 ± 2 kg). Upon arrival (day −1), calves were tagged in the left ear with a unique identification number, weighed, ear notched, and housed overnight in a holding pen with access to hay and water. Ear notches were sent for persistent infection with bovine viral diarrhea virus (PI-BVDV) testing (Cattle Stats, LLC, Oklahoma City, OK) within 48 h of cattle arrival, with no calves testing positive for PI-BVDV. The following morning (day 0), calves were administered respiratory (Pyramid 5, Boehringer Ingelheim Vetmedica, Duluth, GA) and clostridial (Covexin 8, Intervet, In., Madison, NJ) vaccinations, and dewormed (Ivomec Plus, Boehringer Ingelheim Vetmedica). Calves received booster vaccinations on day 14. In addition to administering vaccinations, all calves were branded with a hot iron on the right hip and weighed. The weights recorded on both days (days −1 and 0) were averaged to represent initial weight values.

Within each block, calves were stratified by day −1 BW and allocated randomly to 1 of 8 pens (11 to 13 calves/pen). After the three truckloads (block) were delivered, there were 12 replicate pens per dietary treatment total. Within each block, pens were assigned randomly to a dietary treatment. Calves were housed on 0.42-ha grass paddocks and were fed grain-grain by-product supplements (Table 1) that served as the carrier of the treatments. Treatments consisted of supplemental zinc (360 mg/d), copper (125 mg/d), manganese (200 mg/d), and cobalt (12 mg/d) from complexed (Zinpro Availa 4, Zinpro Corp., Eden Prairie, MN; n = 4 pens/block) or inorganic sources (sulfates; n = 4 pens/block). Within the complexed treatment, the Zinpro Availa 4 was compromised of zinc, manganese, and copper amino acid complexes and cobalt glucoheptonate. Calves were offered supplement formulated for feeding at 0.87 kg DM/d on day 0. When most of the calves in the pen were consuming the supplement at this rate, the pen was switched to a supplement with the appropriate mineral treatment that was formulated for feeding at a 1.32-kg DM/d rate (day 6, block 1; day 4, block 2; day 3, block 3). As per prior changes, pens were moved to supplements (with the appropriate mineral treatment) that were formulated to be fed a 1.76 kg DM/d rate (day 10, block 1; day 8, block 2; day 7, block 3). Changes in the supplement were formulated so the new supplement was approximately equal in nutrients to the original diet, but the percentage of soybean meal was reduced (Table 1). Calves received the 1.76 kg/d supplements for the remainder of the 42-d trial. Bunk readings were evaluated each day to determine when to increase feed delivered. When feed bunks were examined each morning, any refusals from the previous day were collected, weighed, and subsamples frozen for later analyses of DM. Supplement disappearance from the bunk was calculated if there were any refusals. Calves had ad libitum access to bermudagrass hay (7% CP, 73% NDF, 37% ADF, 61 mg Zn/kg, 124 mg Mn/kg, 10 mg Cu/kg: DM basis). Grab samples of supplement and hay were taken for each representing block throughout the trial and were frozen at −20 °C until DM analysis (Tables 2 and 3).

Table 1.

Ingredient composition of grain supplements (DM basis)

	Fed at 0.87 kg DM/d		Fed at 1.32 kg DM/d		Fed at 1.76 kg DM/d
Ingredient	Inorganic	Complexed	Inorganic	Complexed	Inorganic	Complexed
Corn cracked, %	39.7	39.7	52.4	52.4	58.5	58.5
Dried distillers’ grains, %	30	30	30	30	30	30
Soybean meal, %	21	21	10	10	4.7	4.7
Salt, white, %	2.0	2.0	1.5	1.5	1.0	1.0
Molasses, %	2.0	2.0	2.0	2.0	2.0	2.0
Limestone, %	2.4	2.4	2.0	2.0	1.8	1.8
Fat, %	1.0	1.0	1.0	1.0	1.0	1.0
Corn/Rumensin premixa, %	0.8	0.8	0.53	0.53	0.4	0.4
Vitamins A, D, E premixb, %	0.2	0.2	0.14	0.14	0.1	0.1
Vitamin Ec, %	0.1	0.1	0.07	0.07	0.05	0.05
Zinpro Availa-4d, %	—	0.8	—	0.5	—	0.4
Zinc sulfate (35.5% Zn), g/ton	1011	—	676	—	507	—
Manganese sulfate (32% Mn), g/ton	623.5	—	416.7	—	312.5	—
Copper sulfate (25.2% Cu), g/ton	494.7	—	330.7	—	248	—
Cobalt carbonate (46% Co), g/ton	25.9	—	17.4	—	13	—
Sodium selenite (0.99% Se), g/ton	100.8	100.8	67.3	67.3	50.5	50.5

^aPremix provides 22 kg monensin/kg.

^bADE premix contains 880,000 IU/kg vitamin A, 1760,000 IU/kg vitamin D, and 1,100 IU/kg vitamin E.

^cVitamin E contains 44,000 IU/kg.

^dZinpro Availa 4, Zinpro Corp., Eden Prairie, MN (5.15% Zn, 2.86% Mn, 1.8% Cu, 0.18% Co).

Table 2.

Analyzed nutrient composition of hay and grain supplements that provided the dietary treatments, DM basis^a

Item	Hay	Fed at 0.87 kg DM/d		Fed at 1.32 kg DM/d		Fed at 1.76 kg DM/d
		Inorganic	Complexed	Inorganic	Complexed	Inorganic	Complexed
DM, %	95	96	96	97	97	97	97
Zn, mg/kg	61 ± 17	445 ± 1	526 ± 12	400 ± 88	644 ± 39	466 ± 154	387 ± 6
Mn, mg/kg	124 ± 8	133 ± 13	271 ± 12	191 ± 18	199 ± 11	99 ± 38	193 ± 4
Cu, mg/kg	10 ± 2	214 ± 107	173 ± 4	123 ± 6	133 ± 22	107 ± 16	120 ± 3

^aLSMeans ± SEM; Hay, n = 2; 0.87 kg/d, n = 2; 1.32 kg/d, n = 2; 1.76 kg/d, n = 3.

Table 3.

Analyzed composition of hay and grain supplements that provided the dietary treatments, DM basis

Item	Hay	Fed at 0.87 kg DM/d		Fed at 1.32 kg DM/d		Fed at 1.76 kg DM/d
		Inorganic	Complexed	Inorganic	Complexed	Inorganic	Complexed
DM, %	95	96	96	97	97	97	97
CP, %	7	19	21	20	19	17	19
Ash, %	6.82	9.27	9.56	7.96	6.72	6.69	7.54
NDF, %	72.9	27.5	25.2	28.4	27.9	26.5	28.2
ADF, %	36.7	6.7	7.0	8.1	7.1	7.1	7.4

Cattle were observed daily (0800 hours) by trained personnel for signs of bovine respiratory disease (BRD) beginning the morning of the day after processing. Signs of BRD included depression, ocular or nasal discharge, cough, poor appetite, and respiratory distress. Cattle were given a Clinical Attitude Score (CAS) of 0 to 4 by the pen checker who was blinded to dietary treatment (0 = normal, 1 = mild BRD, 2 = moderate BRD, 3 = severe BRD, 4 = moribund). The individual checking pens and scoring cattle remained the same for the entirety of this study. Cattle with a score > 0 were brought to the chute and a rectal temperature was taken. Cattle with a CAS ≥ 1 and a rectal temperature of ≥ 40 °C were treated according to a preplanned antibiotic protocol. The BRD therapy 1 (Nuflor, Merck Animal Health, Rahway, NJ) was administered at 6 mL/45.45 kg BW subcutaneously in the neck and returned to their home pen. If the calf scored a CAS ≥ 1 following BRD therapy 1 and if rectal temperature was ≥ 40 °C, calves would receive BRD therapy 2 (Baytril, Elanco Animal Health, Shawnee, KS) at a rate of 5.7 mL/45.45 kg BW subcutaneously in the neck. At time of reevaluation, if rectal temperature was ≥ 40 °C, the calf would receive BRD therapy 3 (Excenel, Zoetis, Florham Park, NJ) administered 2 mL/45.45 kg BW dosage subcutaneously in the neck for 3 consecutive days. During the 3 d, the calf would be placed in a hospital pen to be monitored. After the 3 d, if the calf remained in the same state of health and rectal temperature was ≥ 40 °C, calves received a final BRD therapy 4 (Draxxin, Zoetis) dosed at 1.1 mL/45.45 kg BW subcutaneously in the neck. After administering BRD therapy 4, if the CAS was ≥ 2 and rectal temperature was ≥ 40 °C, then the calf was considered nonresponsive, and no further treatments were given. If BRD symptoms were present > 21 days after administered the previous therapy, symptoms were considered a new BRD episode and treatment began with BRD therapy 1. Records were kept of all calves pulled from each pen, their CAS, rectal temperatures, and all antibiotics administered. If a calf was treated ≥ 3 times with antibiotics and failed to gain > 0.45 kg/d for the 42-d period, then it was considered and recorded as a chronic calf. If a calf did not live for the duration of the 42-d trial, this was recorded, and the calf was necropsied to determine cause of death.

Weights were recorded initially (days −l and 0) and before supplement feeding (still having access to hay and forage) on the mornings of days 14, 28, 41, and 42 for each load of calves delivered. Average daily gain was calculated for interim and final periods based on the averages of initial and final weights that were recorded on the 2 consecutive days. Blood samples were collected from 6 randomly selected animals in each pen to evaluate serum haptoglobin concentrations. Blood was collected via jugular venipuncture from the same animals on days 0, 14, and 28 using tubes containing a clot activator (BD Inc., Franklin Lakes, NJ). The samples were allowed to sit at room temperature for at least 30 min to allow clot formation. The serum was separated by centrifugation at 2,060 × g for 20 min. Serum was then decanted and stored at −20 °C until time of analysis. Samples were analyzed for haptoglobin concentrations using a commercial ELISA (Immunology Consultants Laboratory Inc., Portland, OR). The intra-assay CV was 5.2 and the inter-assay CV was 20.9.

Liver biopsies were taken on days 5 ± 2 and 43 ± 1 from three calves selected randomly from each pen (same calves were used for each day of sampling). Animals were restrained in a hydraulic squeeze chute, and the 10^th intercostal space on the right side of the animal was identified on the abdomen. An area approximately 10 cm × 10 cm was clipped using an electric clipper to remove the hair for incision. An aseptic technique was used by scrubbing the area with chlorhexidine gauze sponges followed by scrubbing with 70% isopropyl alcohol gauze sponges and a final scrub of an iodine surgical solution. At the site of incision, calves were injected with 5 mL of 2% lidocaine solution under the skin and into the intercostal muscle for numbness. A 5-min wait period was given after the injection to allow the lidocaine to take effect within the surgical area. Following this wait period, a sterile #15 scalpel was used to make a 1-cm incision through the skin. A biopsy needle (16 ga × 10.2 cm or 14 ga × 16.2 cm Tru-Cut Biopsy Needles, Jorgensen Labs Inc., Loveland, CO) was inserted through the incision previously made to obtain liver samples. The same biopsy needle was used to obtain multiple samples from the same calf, until the minimum sample weight for analysis reached 0.05 g. A sterile transfer pipette was used to remove the liver sample from the biopsy needle, and it was carefully placed into individual microtubes and promptly placed on ice. Biopsy needles underwent cold sterilization in between animals. Samples from each collection day were submitted to the Michigan State University Veterinary Diagnostic Laboratory to be dried and used for mineral analysis using mass spectroscopy.

Each batch of grain supplements and all offered hay were sampled to analyze for DM, ash, NDF, ADF, CP, and mineral composition. Samples were dried at 50 °C in a forced air oven until a constant weight to determine dry matter. Dried samples were ground in a Wiley Mill (Arthur H. Thompson, Philadelphia, PA) through a 1-mm screen. Fiber analyses were determined using Ankom 200 Fiber analyzer (ANKOM Technology Corp., Macedon, NY). Nitrogen percentages were used to determine crude protein percentages (ECS 8020 CHNSO dual furnace, NC Technologies). Mineral analyses were performed in duplicate for hay samples and in triplicate for grain samples. To start, 1 ± 0.01 g of hay and 0.5 ± 0.01 g of grain were weighed into 50 mL centrifuge tubes. Then 15 mL of trace mineral grade nitric acid was added to each tube containing sample. Samples underwent wet ash digestion that was performed by covering the tubes with plastic watch glasses and placing them into a heating block. With the heating block, the temperature was set at 80 °C for 15 min, or until all brown gasses had escaped and foaming was not present. After all brown gas had escaped, the temperature was set at 115 °C for 1 hour. Following, the tubes were allowed to cool and were filled to a 45-mL volume with deionized water, inverted, and capped. Samples were analyzed by inductively coupled plasma (ICP) atomic emission spectroscopy (CIROS, Fitchburg, MA) at the University of Arkansas System Division of Agriculture Agricultural Diagnostic Laboratory, Fayetteville, AR.

Statistical Analysis

Data were analyzed as a randomly complete block design with pen identified as the experimental unit. Each block (date of shipment) was treated as the random block effect and treatment was a fixed effect in the model. The subject was identified as the pen within each block. All data were analyzed using various programs of SAS 9.4 (SAS Inst. Inc., Cary, NC). Heifer body weights, average daily gains, and haptoglobin concentrations were analyzed using the MEANS procedure for overall pen averages and the MIXED procedure. Body weights, haptoglobin concentrations, and liver mineral concentrations were analyzed as repeated measures. Kenward-Rogers were specified as the degrees of freedom selection, with compound symmetry as the covariance structure. The model included treatment, day, and the day by treatment interaction. Significance was declared when P ≤ 0.05, with tendencies declared when P > 0.05 and ≤ 0.10.

If there were any interactions that were significant (P ≤ 0.10), treatment means were separated with a t-test using the PDIFF option in SAS. Haptoglobin concentrations were transformed using logarithmic transformation to achieve normal distribution of values. Number of antibiotics administered were also analyzed using the MIXED model. Morbidity data included percentage treated once, twice, thrice, or more; calves deemed chronic, relapses, and mortality. Morbidity data were analyzed using the GLIMMIX procedure with block and treatment in the class statement. Block was considered a random variable and pen within block was the subject. The model included treatment within block as a random variable and the subject as pen within block. Grain supplement and hay sample data were generated using the MEANS procedure. Supplement disappearance averages were analyzed in the MIXED procedure with the subject as pen within block and block as the random effect.

Results and Discussion

Growth Performance and Health

Initial body weights did not differ (P = 0.82) between treatment groups. There tended (P = 0.07) to be a treatment by day interaction for body weights. Body weights were not different on day 0 (P = 0.82) and day 14 (P = 0.36), but heifers supplemented with complexed trace mineral sources had greater body weights on day 28 (P = 0.04) and day 42 (P = 0.05). Calves receiving the complexed trace mineral sources were 4 kg heavier than those receiving inorganic sources by day 42 (Figure 1). There were no treatment differences (P = 0.98) in supplement disappearance from the bunks. Supplement refusals within the first week did not differ (P = 1.00) between treatments. Supplementing cattle for the first 42 d after arrival with complexed trace mineral sources resulted in greater (P = 0.05) overall ADG when compared to supplementing inorganic sources (Table 4). Supportive results were reported by Kegley et al. (2012) in a similar study investigating the effects of supplemental zinc (360 mg/d), copper (125 mg/d), manganese (200 mg/d), and cobalt (12 mg/d) from sulfate or complexed sources in calves over a receiving phase. The current study being replicated in heifers nearly a decade later aligns. Kegley et al. (2012) reported an increase in final body weights and ADG for the calves supplemented with complexed trace mineral sources. In agreement, Dorton et al. (2006) reported by the end of a 28-d feedlot receiving phase, steers that were supplemented with organic (amino acid complexes and cobalt glucoheptonate) trace minerals had greater ADG than steers supplemented with inorganic (sulfates) trace minerals. However, previous research regarding trace mineral supplementation from sulfate or organic sources, growth performance results have not been consistent. A similar study investigated the effects of zinc (360 mg/d), manganese (200 mg/d), and copper (125 mg/d) from three different sources (sulfates, amino acid complexes, and hydroxy sources) during a receiving period (Ryan et al., 2015). This study reported that trace mineral source had no effect on body weights or ADG during the receiving period.

Figure 1.

Effects of complexed or inorganic trace mineral supplementation on body weights during 42-d receiving trial. Treatment × day (P = 0.07), day (P < 0.0001), treatment (P = 0.14). Means within a day without a common superscript differ (P ≤ 0.05). Diets supplemented for 42 d with 360 mg Zn, 200 mg Mn, 125 mg Cu, and 12.5 mg Co per calf daily from complexed (Zinpro Availa 4, Zinpro Corp.) or inorganic (sulfate) sources.

Table 4.

Effect of complexed or inorganic trace mineral supplementation on growth performance of newly received calves^a (n = 12 pens/treatment)

Item	Complexed	Inorganic	SEM	P-value
ADG, kg/d
Days 0 to 14	0.70	0.61	0.06	0.32
Days 14 to 28	0.85	0.70	0.08	0.20
Days 28 to 42	0.76	0.72	0.05	0.58
Days 0 to 42	0.78	0.70	0.03	0.05

^aDiets supplemented for 42 d with 360 mg Zn, 200 mg Mn, 125 mg Cu, and 12.5 mg Co per calf daily from complexed (Zinpro Availa 4, Zinpro Corp.) or inorganic (sulfate) sources.

In the present study, cattle supplemented with inorganic trace mineral sources had greater (P = 0.03) BRD morbidity incidence (Table 5). The percentage of calves treated at least once for BRD was less (P = 0.03) for those supplemented with complexed trace mineral sources. The timing of antimicrobial usage did not differ between treatments (P ≤ 0.60). Deaths occurred in both treatments during the receiving trial (complexed, n = 2; inorganic, n = 4). Bacteria cultures from necropsies revealed diagnosis of BRD (complexed, n = 2; inorganic, n = 3) or acute acidosis (inorganic, n = 1). Rectal temperatures at time of antimicrobial administration remained the same for both treatments (P ≥ 0.12). Kegley et al. (2012) also reported a tendency for a decrease in percentages of the calves receiving a second antibiotic treatments for BRD compared to the sulfate supplemented calves.

Table 5.

Effect of complexed or inorganic trace mineral supplementation on health of newly received cattle^a

Item	Complexed	Inorganic	SEM	P-value
Cattle treated at least once, %	46.2	57.7	3.6	0.03
Day of 1st treatment	5	6	0.7	0.60
Rectal temperature at 1st treatment, °C	40.78	40.71	0.14	0.50
Cattle treated at least twice, %	14	21.5	3.3	0.12
Day of 2nd treatment	14	16	1.1	0.34
Rectal temperature at 2nd treatment, °C	40.44	40.64	0.22	0.24
Relapse, %	30.7	38.2	5.9	0.38
Cattle treated at least 3 times, %	9.7	9.6	2.7	0.98
Day of 3rd treatment	18	21	2.3	0.42
Rectal temperature at 3rd treatment, °C	40.79	40.40	0.31	0.12
Cattle treated 4 times, % b
Chronic cattle, %	7.6	9.6	2.4	0.58
Dead cattle, %c
Number of antibiotic treatmentsd	0.75	0.93	0.09	0.18

^aDiets supplemented for 42 d with 360 mg Zn, 200 mg Mn, 125 mg Cu and 12.5 mg Co per calf daily from complexed (Zinpro Availa 4, Zinpro Corp.) or inorganic (sulfate) sources.

^bGLIMMIX model did not converge: n = 3 for organic vs. n = 8 for inorganic.

^cGLIMMIX model did not converge: n = 2 for organic vs. n = 4 for inorganic.

^dAverage number of antibiotic treatments administered per calf in the respective dietary treatment.

Additionally, Chirase and Greene (2001) concluded from a mineral study, with high density confinement rearing of livestock, that there are additional important roles for nutrients rather than only supporting growth and reproductive functions. Chirase and Greene (2001) explain that appropriate mineral nutrition can decrease infectious diseases and concomitant stresses. This ultimately concluded that appropriate mineral nutrition could limit the use of antibiotics and other anti-infection drugs in livestock production. From this, both treatments included in this receiving study provided iso levels of adequate trace mineral supplementation to meet requirements which gave opportunity to reveal bioavailability differences between treatments. However, results in previous literature have not been consistent when investigating trace mineral supplementation source. Lippolis et al. (2017) observed that supplementing beef cattle with inorganic or complexed sources of cobalt, copper, manganese, and zinc during a 58-d receiving period did not impact cattle performance and health responses. Even though Dorton et al. (2006) reported a difference in ADG, there were no effects of trace mineral source on morbidity or the number of treatments per morbid animal throughout the receiving period. Accompanied with growth performance, Ryan et al. (2015) reported that trace mineral source had no effect on BRD incidence, average antibiotic cost per calf, or the percentage of calves that relapsed.

Haptoglobin Concentrations

Haptoglobin concentrations decreased (day, P < 0.001) throughout the 42-d trial (Figure 2). By day 28, cattle supplemented with complexed trace mineral sources had decreased (P = 0.03) concentrations. Haptoglobin, being an acute-phase protein, contributes to restoring homeostasis and limiting microbial growth to calves subject to infection, inflammation, or stress (Moisá et al., 2018). Previous research states that copper-deficient cattle have a suppressed response that alters the normal acute phase reaction which results in a noticeable increase in haptoglobin concentrations (Arthington and Ranches, 2021). Harvey et al. (2021) found when comparing complexed sources of trace minerals versus inorganic sources, there was an increase in plasma cortisol and haptoglobin concentrations in animals consuming inorganic trace mineral supplementation. Supporting data suggest that supplementing complexed sources of trace minerals results in reduced haptoglobin concentrations over time in calves subject to infection or stress.

Figure 2.

Effects of complexed or inorganic trace mineral supplementation on haptoglobin concentrations in calves. Day (P = 0.0002), treatment (P = 0.07), treatment × day (P = 0.36). Diets supplemented for 42 d with 360 mg Zn, 200 mg Mn, 125 mg Cu, and 12.5 mg Co per calf daily from complexed (Zinpro Availa 4, Zinpro Corp.) or inorganic (sulfate) source.

Liver Mineral Concentration

In this receiving trial, the source of trace mineral supplementation had no effect (P ≥ 0.20) on liver mineral concentrations (Figure 3) and there were no treatment × day interactions (P ≥ 0.35). Although organic trace mineral forms are expected to have enhanced absorption, retention, and biological activity compared with sulfate minerals (Spears, 1996), the effects of supplementing organic or inorganic sources of trace mineral on liver mineral status of beef cattle have been variable. The liver is an organ that is often used to predict the status of various trace minerals in animals (McDowell, 1992; Spears et al., 2022). Mineral turnover rates vary from tissue to tissue but are generally greatest in the liver and slowest in the bone. However, the rate of change in trace mineral concentrations in the bovine liver due to environmental and nutritional factors is still unclear.

Figure 3.

Liver mineral concentration comparison during the receiving period (n = 72). Diets supplemented for 42 d with 360 mg Zn, 200 mg Mn, 125 mg Cu, and 12.5 mg Co per calf daily from complexed (Zinpro Availa 4, Zinpro Corp.) or inorganic (sulfate) sources.

It is important to note that in the current project the first liver samples were taken on day 5 after calves began consuming supplements and had undergone the stress at processing after arrival on day 0. Galyean et al. (1999) stated that most minerals need to be increased in receiving diets to compensate for low feed intake by stressed calves. On day 5, liver concentrations of selenium, copper, zinc, and manganese were below levels that are considered adequate by Puls (1988). By day 43 of calves receiving supplement, day effects were present (day, P < 0.01) showing liver concentrations of copper, cobalt, and selenium had increased similarly for both dietary treatments.

Liver copper concentrations increased (day, P < 0.01) by day 43, exceeding adequate concentration (Puls, 1988), suggesting that both complexed and inorganic sources influenced mineral status. The concentration range considered adequate in dry liver by Puls (1988) is from 125 to 600 µg/g, marginal if concentrations are between 33 and 125 µg/g and considered deficient if concentrations fall below 33 µg/g. Spears et al. (2022) also stated that liver copper concentrations are the best indicator of status in ruminants, and copper can readily be mobilized from the liver into the blood to supply copper for biochemical reactions. To support, McDowell (1992) stated that the concentration of copper in the liver of ruminants is directly correlated to the bioavailability of copper in the diet. It is important to consider that intakes of zinc, molybdenum, iron, and sulfur can affect copper utilization (McDowell, 1992). Liver molybdenum concentrations in the current study were not affected (P > 0.43) by treatment, day, or the treatment × day interaction. Nockels et al. (1993) conducted a study determining whether copper or zinc balance would be affected by feeding either organic amino acid complexes (ZnMet and CuLys) or inorganic (ZnSO₄ and CuSO₄) sources of zinc and copper before and after stressing calves. Calves fed CuLys had 53% greater apparent copper absorption and increased retention during repletion when compared to the calves fed CuSO₄. A copper deficiency or imbalance can alter enzyme activity and alter the function of specific organs thus impairing involved metabolic pathways that include overall immune function (Paterson and Engle, 2005).

Liver zinc concentrations decreased (day, P < 0.01) by day 43, but remained within the adequate concentration range for the duration of the trial. Both treatments decreased similarly; calves supplemented with complexed trace mineral sources dropped from 162 to 111 µg/g and inorganic calves dropped from 197 to 121 µg/g. The concentration range considered adequate by Puls (1988) is 25 up to 200 µg/g. Similar results were found by Smerchek et al. (2023) when investigating organic trace mineral supplementation to steers in a 42-d receiving trial. Aligning with this study, Smerchek et al. (2023) reported a noticeable decrease in zinc concentrations by day 42. However, Arthington and Ranches (2021) state that zinc lacks a reliable tissue pool for indicating status. In contrast, Kincaid (1999) stated that liver zinc concentrations are sensitive to zinc intake. In the liver, calves readily absorb and bind large amounts of zinc as metallothionein in response to elevated zinc intakes (Kincaid et al., 1976). Spears et al. (2022) explained in a review that undergoing acute stress or infection may result in decreased liver zinc concentrations in cattle suggesting the values reported with this study represent a normal physiological response. It is important to consider this when comparing liver samples from days 5 and 43 in this study. It has been reported that zinc retention becomes negative during stress caused by feed and water deprivation (Nockels et al., 1993). Furthermore, Nockels et al. (1993) reported that copper and zinc retention was decreased in steers when stressed and accompanied with feed and water restriction. This physiological response may explain the decrease in zinc concentrations in this experiment.

Manganese concentrations tended to decrease similarly by day (day, P = 0.09), but there were no treatment or treatment × day interactions during this receiving trial. In cattle, if manganese concentrations in the liver are below 7 µg/g it is considered deficient according to Puls (1988). Calves on both treatments were slightly above deficient concentrations when sampled on day 5, but by the end of the receiving trial both treatments had decreased manganese concentrations (P = 0.95). However, Kincaid (1999) stated that when assessing liver manganese concentrations, it should be considered that the manganese in the liver is transient. Plasma manganese is absorbed in the liver, then excreted as endogenous losses through bile. Even in animals exhibiting classical signs of manganese deficiency such as impaired reproduction or skeletal disorders, measures of manganese status have been variable among studies (Spears, 2022).

Cobalt concentrations increased (P < 0.01) revealing a day effect for both treatments during the 42-d trial. Cobalt liver concentrations were 0.96 µg/g for complexed supplemented calves and 0.68 µg/g for inorganic supplemented calves at the conclusion of the trial. There were no differences between treatments (P = 0.20). Due to the metabolic role of cobalt, assessment of the animal’s nutriture often centers on measures of vitamin B12 status. Difficulty assessing tissue cobalt status persists and current literature was not able to provide values for adequate tissue concentrations.

Although selenium concentrations increased (day, P = 0.01), the values remained below concentrations considered adequate for both treatments according to Puls (1988). Selenium was delivered at the same rate to both treatment groups as sodium selenite resulting in similar liver concentrations (P = 0.79). Adequate concentrations of selenium in the liver are above 1.25 µg/g, yet the highest concentration detected in the current 42-d trial was 1.11 µg/g. Cattle are considered marginally deficient in selenium if concentrations fall between 0.60 and 1.25 µg/g. The concentrations were not severely deficient, but marginally deficient calves may display weakness and low vigor.

To conclude, the source of trace mineral supplemented had no effect on liver mineral concentrations during the 42-d receiving trial. These results demonstrate the variability observed in trace mineral concentrations in liver, and highlight the continued need to better understand factors that influence liver mineral concentrations. These calves experienced stress through sale barn exposure, commingling, and transportation which may have influenced differences in trace mineral source bioavailability. However, replacing inorganic sources with complexed sources of trace minerals (zinc, copper, manganese, and cobalt) improved growth performance and decreased morbidity treatments and associated medication costs during the 42-d receiving phase.

Glossary

Abbreviations

ADF

acid detergent fiber

ADG

average daily gain

BRD

bovine respiratory disease

BW

body weight

CP

crude protein

ELISA

enzyme-linked immunosorbent assay

NDF

neutral detergent fiber

PI-BVDV

persistent infection with bovine viral diarrhea virus

Conflict of Interest Statement

J.R. is directly associated with the funding organization. The authors have not stated any other conflicts of interest.