Invited review: Advances in nisin use for preservation of dairy products. By Ibarra-Sánchez et al., page 2041. Dairy products, in particular nonfermented products, are prone to contamination with foodborne pathogens, such as Listeria monocytogenes, Staphylococcus aureus, and Salmonella spp. Nisin, a widely used antimicrobial, is effective in certain dairy products. In this review, we discuss the factors limiting the use of nisin in dairy products and summarize current strategies to enhance nisin effectiveness in low-acid and whole-fat dairy products.
https://doi.org/10.3168/jds.2019-17498.
Toxicity study and blood pressure–lowering efficacy of whey protein concentrate hydrolysate in rat models, plus peptide characterization. By Hussein et al., page 2053. Whey protein concentrate was enzymatically digested using alcalase. The hydrolysate was assayed for toxicity and blood pressure–lowering efficacy in rat models, followed by identification of angiotensin-converting enzyme–inhibitory peptides. In vivo studies showed that whey protein concentrate hydrolysate was nontoxic and able to significantly reduce blood pressure in hypertensive rats. Two peptides from whey protein concentrate—VLSELPEP (half-maximal inhibitory concentration = 0.049 mM) and LEQVLPRD (half-maximal inhibitory concentration = 0.043 mM)—showed prominent in vitro angiotensin-converting enzyme inhibition. These findings demonstrated the potential of whey protein concentrate hydrolysate and its peptides for incorporation into daily foods as functional ingredients with antihypertensive activity.
https://doi.org/10.3168/jds.2019-17462.
Effects of the vat pasteurization process and refrigerated storage on the bovine milk metabolome. By Zhu et al., page 2077. In this study, the evolution of cow milk metabolites throughout the vat pasteurization process (63°C for 30 min) and subsequent refrigerated storage was studied using a combination of different techniques. The vat pasteurization process was proven to be a mild and efficient means for milk preservation, as this processing caused minor changes in the milk metabolites. Moreover, the pasteurized milk samples exhibited stable properties during the first 8 d of refrigerated storage. Some compounds, such as some fatty acids, organic acids, peptides, and ketones, increased in the final stage of storage.
https://doi.org/10.3168/jds.2019-17512.
Short communication: Sensory characteristics and volatile organic compound profile of high-moisture mozzarella made by traditional and direct acidification technology. By Natrella et al., page 2089. The sensory characteristics and volatile compound profile of high-moisture cow mozzarella manufactured by traditional and direct-set technology were investigated. The 2 types of cheese were clearly discriminated by the panelists, and the differences were reflected in the volatile compound profiles. The profile of traditional mozzarella was much more complex, and 3-methyl-butanal, nonanal, ethyl acetate, and phenylethanol were the most important odor-active compounds. The cheese is in the process of acknowledgment as a Protected Designation of Origin product by the European Commission.
https://doi.org/10.3168/jds.2019-17059.
Virulence factors and antimicrobial resistance of Staphylococcus aureus isolated from the production process of Minas artisanal cheese from the region of Campo das Vertentes, Brazil. By Castro et al., page 2098. Few reports exist that describe the virulence factors and antimicrobial resistance profile of Staphylococcus aureus isolated from Brazilian artisanal cheese at specific points in the production chain. In this study, Staphylococcus aureus isolated from raw milk, endogenous starter cultures, Minas artisanal cheese, and cheese handlers from Campo das Vertentes, Brazil, presented toxigenic and biofilm-forming potential. However, none of the staphylococcal isolates presented a pattern of multidrug resistance to antimicrobials commonly used for veterinary and human applications.
https://doi.org/10.3168/jds.2019-17138.
Short communication: Clostridial spore counts in vat milk of Alpine dairies. By Burtscher et al., page 2111. Clostridia are known to cause severe cheese spoilage; therefore, milk used for the production of hard and semihard cheese must not contain clostridial endospores. Silage, a carrier of endospores, often is prohibited as a feed. Using modern methodology, we monitored clostridial endospore levels in vat milk of 4 Alpine dairies throughout the summer grazing period. Surprisingly low spore counts of clostridia and no blowing defects in cheese were observed. This study confirmed that the prohibition of silage feeding and good farming practices are an effective means to minimize clostridial endospore concentrations in milk and quality defects in cheese.
https://doi.org/10.3168/jds.2019-17559.
Microscopic analysis and microstructural characterization of the organic and inorganic components of dairy fouling during the cleaning process. By Guerrero-Navarro et al., page 2117. The thermal treatment of milk produces fouling, which can accumulate on contact surfaces. The elimination of fouling is expensive, which is a serious problem in the dairy industry. Therefore, studying the composition and microscopic structure of fouling could be of great help to improve cleaning processes in this industry. This paper presents the composition and structure of dairy fouling in different setups. A new improved enzymatic formula for eliminating fouling is also tested as a real alternative for use in the dairy industry.
https://doi.org/10.3168/jds.2019-16957.
Studying stirred yogurt microstructure using optical microscopy: How smoothing temperature and storage time affect microgel size related to syneresis. By Gilbert et al., page 2139. Industrial shearing and smoothing conditions for stirred yogurt are complicated to reproduce, and little is known about how they affect stirred yogurt structure. This study demonstrated that cooling yogurt to 20°C before smoothing reduced yogurt graininess and heterogeneity, which limited syneresis (serum separation). Moreover, the use of whey protein concentrate, which is less concentrated in proteins but less expensive than whey protein isolate, was a good way to adjust the casein:whey protein ratio because the whey protein source had little effect.
https://doi.org/10.3168/jds.2019-16787.
Microbial transglutaminase alters the immunogenic potential and cross-reactivity of horse and cow milk proteins. By Fotschki et al., page 2153. Horse milk is a very attractive alternative for scientific research to address the issue of cow milk allergy due to its protein profile. This study shows that horse milk was less reactive than cow milk with animal and human allergic patient sera. Transglutaminase reduced the β-lactoglobulin and increased the α-casein and immunoreactivity of cow and horse milk. The effect of an enzyme on immunoreactivity depends on enzyme quantity and milk protein type.
https://doi.org/10.3168/jds.2019-17264.
Effect of amount of milk replacer fed and the processing of corn in starter on growth performance, nutrient digestibility, and rumen and fecal fibrolytic bacteria of dairy calves. By van Niekerk et al., page 2186. We investigated the effect of feeding dairy calves 0.75 or up to 1.50 kg of milk replacer/d in combination with slow or rapid rumen fermentable starch in calf starter (whole vs. flaked corn). Feeding less milk replacer increased the digestion of fiber and organic matter from starter postweaning and increased the proportion of fibrolytic bacteria in the rumen and fecal contents during wk 5. Growth from birth to 4 mo of age was unaffected by treatments.
https://doi.org/10.3168/jds.2019-17372.
Effect of prepartum energy intake and supplementation with ruminally protected choline on innate and adaptive immunity of multiparous Holstein cows. By Zenobi et al., page 2200. Choline has been declared an essential nutrient in many species. Cows do not seem to be an exception. Prepartum diets with moderate to high energy content have shown to be detrimental to immune function and activity. Feeding rumen-protected choline (RPC) to cows overfed energy prepartum modulated their inflammatory state during the postpartum period compared with cows not fed RPC. Regardless of prepartum energy intake, cows fed RPC exhibited less inflammation, as evidenced by decreased rectal temperature and decreased plasma concentrations of haptoglobin and fibrinogen. Collectively, these data indicate that transition cows supplemented with RPC experienced less inflammation.
https://doi.org/10.3168/jds.2019-17378.
Effects of milk replacer feeding rates on growth performance of Holstein dairy calves to 4 months of age, evaluated via a meta-analytical approach. By Hu et al., page 2217. A database of 10 published studies with 491 Holstein calves was constructed to evaluate effects of feeding milk replacer at moderate or high rates (0.64–0.66 or 0.92–1.07 kg of dry matter/d) on performance of calves. When fed at high as opposed to moderate rates, preweaning body weight and hip width gain were greater, but the opposite was true in calves from 56 to 112 d. Postweaning digestibility of dry matter and neutral detergent fiber were less in calves fed high rather than moderate rates of milk replacer. Over the 112-d period, calves fed at high rates of milk replacer were 2.4 kg heavier than those fed at a moderate rate but tended to have less structural growth.
https://doi.org/10.3168/jds.2019-17206.
Postruminal infusions of amino acids or glucose affect metabolisms of splanchnic, mammary, and other peripheral tissues and drive amino acid use in dairy cows. By Omphalius et al., page 2233. In dairy cows, better knowledge of use of amino acids to synthesize all proteins by different tissues is required to improve the efficiency of use of protein (i.e., the proportion of digested proteins recovered in exported proteins). Various dietary protein and energy conditions changed the coordination of different tissues involved in the use of amino acids, suggesting that amino acid fate within each tissue should be considered to better predict the efficiency of use of amino acids.
https://doi.org/10.3168/jds.2019-17249.
Fatty acid profile of phospholipids and sphingomyelin in milk and regulation of sphingomyelin synthesis of mammary glands in cows receiving increasing levels of crushed sunflower seeds. By Lashkari et al., page 2255. Milk fat composition is affected by the feed given to dairy cows. In the present experiment, we investigated whether seeds of oil plants such as sunflower affected the content of 2 types of lipids, phospholipids and sphingomyelin, in the membrane surrounding the tiny fat droplets in milk. This is of interest because the 2 types of lipids mentioned reduce the intestinal absorption of cholesterol. We found that cows fed high levels of sunflower seeds did not produce increased amounts of the 2 types of beneficial lipids.
https://doi.org/10.3168/jds.2019-17157.
Effects of feeding a quebracho–chestnut tannin extract on lactating cow performance and nitrogen utilization efficiency. By Aguerre et al., page 2264. This experiment investigated the long-term effect of adding a quebracho–chestnut tannin mix to dairy diets on lactating cow performance and nitrogen (N) efficiency. Increasing tannin in the diet from 0 to 1.80% of dry matter reduced feed efficiency but reduced N excretion from urine. When fed at 0.45% of diet dry matter, tannin extracts had a positive effect on milk protein content but no effect on protein yield. Thus, a tannin extract mixture from quebracho and chestnut may reduce environmental labile urinary N excretion when fed at a level that had no effect on milk protein content and at the expense of a lower feed utilization efficiency.
https://doi.org/10.3168/jds.2019-17442.
Responses to rumen-protected choline in transition cows do not depend on prepartum body condition. By Bollatti et al., page 2272. It is often suggested that supplementing choline benefits cows at an increased risk of fatty liver, such as overconditioned cows. Dairy cows supplemented with 12.9 g of choline ion/d in a rumen-protected form from 21 d prepartum to 21 d postpartum had improved yields of milk and milk components and increased efficiency of feed utilization in the first 105 d postpartum irrespective of the degree of fatness prepartum. Responses to choline were not mediated by improvements in metabolism or health. Choline may have effects other than those on hepatic lipid metabolism that explain improvements in lactation performance.
https://doi.org/10.3168/jds.2019-17302.
Supplementation of nicotinic acid to prepartum Holstein cows increases colostral immunoglobulin G, excretion of urinary purine derivatives, and feed efficiency in calves. By Aragona et al., page 2287. A significant amount of colostrum in the United States and other countries does not meet industry quality standards for immunoglobulin G and bacterial counts. High-quality colostrum is important for the immunologically naïve newborn calf, not only for survival but also for successful growth and future production. Previously, prepartum supplementation with 48 g of nicotinic acid/d increased colostral immunoglobulin G by 18%. This study investigated the effects of 0, 16, 32, and 48 g of nicotinic acid/d on colostrum quality and calf performance. In summary, increased levels of nicotinic acid increased colostrum quality, and 32 g/d increased feed efficiency in calves.
https://doi.org/10.3168/jds.2019-17058.
Effects of oregano essential oil on in vitro ruminal fermentation, methane production, and ruminal microbial community. By Zhou et al., page 2303. Different oregano essential oil (OEO) inclusion rates were investigated for effects on ruminal in vitro fermentation, total gas, methane production, and bacterial communities. Digestibility of dry matter and neutral detergent fiber was highest for 52 mg/L OEO, whereas digestibility of acid detergent fiber was highest for 91 mg/L OEO compared with 0 mg/L OEO. Inclusion rate of OEO can modify the bacterial community and fermentation through altering ammonia and volatile fatty acid concentrations while reducing methane emissions. These results suggested that OEO supplementation extensively alters the ruminal bacterial community and that 52 mg/L OEO may be an optimal feeding rate for future studies.
https://doi.org/10.3168/jds.2019-16611.
Calf starter containing a blend of essential oils and prebiotics affects the growth performance of Holstein calves. By Liu et al., page 2315. Essential oils extracted from specific plants can exhibit antimicrobial properties that make them potential antibiotic alternatives and growth promoters. Two calf starters were formulated without and with an essential oil prebiotic blend and fed to neonatal calves from birth through 70 d of age. Average daily gain, dry matter intake, and feed conversions were greater for calves fed the essential oil combination compared with the control-fed calves. The use of an essential oil and prebiotic combination demonstrates a plausible alternative for enhancing calf growth, ruminal development, and gut health.
https://doi.org/10.3168/jds.2019-16647.
Effect of starter form, starch concentration, and amount of forage fed on Holstein calf growth from 2 to 4 months of age. By Aragona et al., page 2324. To support optimal body weight gain and frame growth, young calves should be fed easily digestible feeds, especially because of the limited capacity of the rumen. We investigated the effects of feeding 2 starter forms with 2 different starch levels with either 5% chopped hay or ad libitum long hay. Ad libitum hay intake was highly variable. High-starch, low-fiber textured starters supported ≥9% more growth than low-starch pelleted starters. Restricted feeding of starter with ad libitum long grass hay reduced dry matter intake by 13 to 17%, average daily gain by 20%, and hip width change by 10 to 23% compared with 95% starter blended with 5% chopped hay fed ad libitum.
https://doi.org/10.3168/jds.2019-17474.
Effects of ensiling time on corn silage neutral detergent fiber degradability and relationship between laboratory fiber analyses and in vivo digestibility. By Hristov et al., page 2333. Degradability of corn silage neutral detergent fiber (NDF) linearly decreased from 0 to 150 d of ensiling time, primarily caused by decreases in concentration of hemicellulose and NDF-bound protein. Common laboratory analyses were poorly correlated with in situ rumen degradability of silage NDF. We found a good relationship between dietary concentration of indigestible NDF and in vivo apparent total-tract dietary NDF digestibility from 16 experiments with lactating dairy cows, but the relationship with undegraded NDF was poor or nonexistent.
https://doi.org/10.3168/jds.2019-16917.
Comparison of microbial fermentation data from dual-flow continuous culture system and omasal sampling technique: A meta-analytical approach. By Brandao et al., page 2347. This metaanalysis aimed to compare microbial fermentation responses in vitro, using the dual-flow continuous culture system (DFCCS), with in vivo data. We used 155 articles, in which 97 used DFCCS and 58 used the omasal sampling technique. Four independent variables were regressed against 12 dependent variables related to ruminal carbohydrate and nitrogen metabolisms, and the effect of method (DFCCS vs. omasal sampling technique) was tested. Out of 41 regressions developed, method affected only 14 estimates of the intercept and 2 estimates of slope, meaning that the functional relationship between the responses is similar; however, the magnitude might be different in some cases.
https://doi.org/10.3168/jds.2019-17107.
Feeding a diet with corn distillers grain with solubles to dairy cows alters manure characteristics and ammonia and hydrogen sulfide emissions from manure. By Lee et al., page 2363. Information about manure characteristics and gas emissions from manure after feeding a diet containing corn distillers grain with solubles (DG), and therefore its environmental impacts, is not available in dairy cows. A 28.8% DG diet compared with a soybean meal–based diet (control) decreased urinary N excretion and lowered urine pH without affecting fecal output and N excretion. This resulted in reduced NH3 emission from DG manure during the incubation. The DG diet increased fecal and urinary S excretion and, therefore, increased S concentration in DG manure. The high S content of DG manure mainly caused increased H2S emissions from manure.
https://doi.org/10.3168/jds.2019-17524.
Influence of proportion of wheat in a pasturebased diet on milk yield, methane emissions, methane yield, and ruminal protozoa of dairy cows. By Moate et al., page 2373. Increasing the proportion of wheat in the diet of dairy cows reduced their methane emissions, but this occurred only when wheat constituted more than 30% of the diet. This environmental advantage was mirrored in increases in milk yield but with reduced milk fat concentration. Contrary to previous reports, methane emissions were not associated with the number of ruminal protozoa.
https://doi.org/10.3168/jds.2019-17514.
Effects of jugular infused methionine, lysine, and histidine as a group or leucine and isoleucine as a group on production and metabolism in lactating dairy cows. By Yoder et al., page 2387. Methionine, lysine, and histidine as a group and isoleucine and leucine as a group independently and additively increased milk protein yield in dairy cows. The independent milk protein responses are in direct contradiction to the single limiting essential amino acid theory. Isoleucine and leucine also increased milk and energy-corrected milk yield as well as mammary plasma flow, indicating increased mammary anabolic activity from the increased supply of isoleucine and leucine. These results suggest that supplies of leucine and isoleucine should be considered when feeding diets that are deficient in metabolizable protein in addition to methionine, lysine, and histidine.
https://doi.org/10.3168/jds.2019-17082.
In vitro gas production and rumen fermentation profile of fresh and ensiled genetically modified high–metabolizable energy ryegrass. By Winichayakul et al., page 2405. Genetically modified (GM) ryegrass with elevated leaf lipid content was developed to increase metabolizable energy and enhance forage feeding value. In this paper, we present the changes in nutritional profile of this GM ryegrass, which included a 59 to 98% increase in lipid and a 6 to 6.8% increase in gross energy. To obtain preliminary evidence for an animal feeding trial of this novel ryegrass, we examined in vitro gas production and rumen fermentation profiles of both fresh and ensiled material from both non-GM and GM high-lipid ryegrass. We finish by discussing the potential impact on the pastoral industry from this novel GM ryegrass.
https://doi.org/10.3168/jds.2019-16781.
Factors affecting levels of volatile 4-alkyl branched-chain fatty acids in sheep milk from 2 contrasting farming systems in New Zealand. By Teng et al., page 2419. Sheep milk has a characteristic “sheepy” flavor that limits the consumption of sheep meat and milk products by some consumers. This sheepy flavor is caused predominantly by high levels of volatile 4-alkyl branched-chain fatty acids (vBCFA). We investigated the factors affecting the levels of vBCFA in sheep milk in a case study. We found that levels of vBCFA were associated with lactation stage and the proportion of lucerne silage fed to ewes. Milk from fully housed mid-lactation ewes had higher flavor values than milk from pasture-grazed late-lactation ewes because of its higher total amounts of vBCFA.
https://doi.org/10.3168/jds.2019-17192.
Realization of breeding values for milk fatty acids in relation to seasonal variation in organic milk. By Poulsen et al., page 2434. The aim of this study was to investigate whether extreme breeding values of sires for percentage of saturated fatty acids (SFA%) are reflected in the detailed milk fatty acid (FA) profile of their daughters. Milk samples were collected from 194 cows from 7 organic herds, and the detailed FA composition was measured using gas chromatography. The results showed that use of mid-infrared spectroscopy to predict SFA% for estimated breeding values (EBV) will most likely display a correlated response with the detailed FA composition in milk. A combined action of feeding and genetics resulted in a 10-percentage-unit difference, on average, when comparing milk SFA% from daughters of high SFA% EBV sires during indoor spring feeding from one farm to milk SFA% from daughters of low SFA% EBV sires during summer from another farm.
https://doi.org/10.3168/jds.2019-17065.
Can greenhouse gases in breath be used to genetically improve feed efficiency of dairy cows? By Difford et al., page 2442. Genetic parameters were estimated for methane and carbon dioxide in the breath of cows during milking along with dry matter intake, production traits, and feed efficiency in first-parity Holstein cows in Denmark and the Netherlands. Greenhouse gas traits were found to be heritable and genetically correlated with dry matter intake and production traits. However, the sign of genetic correlations between greenhouse gas traits and feed efficiency depended on the definition of feed efficiency and the specific population. Although greenhouse gas traits show potential to serve as indicator traits for feed efficiency traits, more research is required to elucidate whether breeding for more feed-efficient cows will result in more climate-friendly cows.
https://doi.org/10.3168/jds.2019-16966.
Genotype-by-environment (temperature-humidity) interaction of milk production traits in Australian Holstein cattle. By Cheruiyot et al., page 2460. Dairying in Australia is practiced in diverse climatic conditions, which means that re-ranking of bulls could occur across environments that vary in temperature and humidity, so that the performance of daughters of the best bulls in cooler environments may not always be the best in hotter and humid climates. Our results show that re-ranking does exist for some bulls, but the current extent of re-ranking does not justify having separate breeding programs for high heat stress environments. We also observed more re-ranking of bulls in recent years, and therefore routine monitoring is recommended, especially in anticipation of increased climate change.
https://doi.org/10.3168/jds.2019-17609.
Genomic prediction of residual feed intake in US Holstein dairy cattle. By Li et al., page 2477. We estimated genomic breeding values for residual feed intake (RFI) of US Holstein dairy cattle. Feed accounts for much of the cost of milk production, so breeding cows that require less feed can help improve the profitability and sustainability of dairy operations. A new RFI model, 2 genomic prediction methods, and 2 types of genotype chips (60k and high density) were used to estimate genomic breeding values and assess prediction reliability. The reliability of prediction was generally low, but the addition of genomic information increased reliability compared with using only pedigree information. Continued collection of feed intake data is necessary to ensure that successive generations have higher reliabilities. Focusing RFI data collection on relatives of elite bulls that will have the greatest genetic contribution to the next generation will produce more gains and profit.
https://doi.org/10.3168/jds.2019-17332.
Estimation of genetic parameters for mid-infrared—predicted lactoferrin and milk fat globule size in Holstein cattle. By Nayeri et al., page 2487. This study examined the genetic variation of mid-infrared-predicted milk lactoferrin and milk fat globule size. The results indicated moderate heritability for both traits and moderate genetic correlations between lactoferrin and protein percentage and between milk fat globule size and fat percentage. Thus, these mid-infrared-predicted values may provide additional information for selecting for fine milk components in Holstein cattle.
https://doi.org/10.3168/jds.2019-16850.
Combined use of milk infrared spectra and genotypes can improve prediction of milk fat composition. By Wang and Bovenhuis, page 2514. This study investigated the prediction of milk fat composition based on the combined use of milk infrared (IR) spectroscopy and genotypes of dairy cows. We demonstrated that prediction accuracy of milk fat composition based on IR spectroscopy can be improved by adding genotypic information from 3 polymorphisms. We hypothesized that prediction accuracy of milk fat composition can be further improved by combining milk IR spectra with genomic breeding values. The same principles can be applied to improve prediction accuracy of other traits.
https://doi.org/10.3168/jds.2019-16784.
Observed progeny performance validates the benefit of mating genetically elite beef sires to dairy females. By Berry and Ring, page 2523. Given the growing interest in beef from dairy herds and the recent availability of breeding goals to rank beef sires for use on dairy females, the validation of such tools is paramount. In the present study, performance data from the progeny of beef sires mated to dairy females were used to compare matings from beef sires that were deemed to be genetically divergent at the time of mating. Results confirmed the expectation that the progeny of dairy females mated to genetically elite beef sires outperformed their genetically inferior counterparts.
https://doi.org/10.3168/jds.2019-17431.
Usefulness of milk mid-infrared spectroscopy for predicting lameness score in dairy cows. By Bonfatti et al., page 2534. We investigated the potential of milk infrared spectra to classify sound and not-sound cows in a data set of 3,771 cows. The use of milk midinfrared spectra, coupled with readily available on-farm data, correctly classified only around 60% of the cows. Moreover, the genetic correlation between the actual lameness score and the lameness score predicted using infrared milk spectra in 8,535 cows was not significantly different from zero. These results are too poor to envisage a practical application of these models in the near future as on-farm tools to identify lame cows or to provide an indicator trait for actual lameness for animal breeding.
https://doi.org/10.3168/jds.2019-17551.
Increased autophagy mediates the adaptive mechanism of the mammary gland in dairy cows with hyperketonemia. By Li et al., page 2545. Autophagy status and its regulation pathways in the mammary gland of dairy cows with hyperketonemia were studied. Ten healthy cows and 10 cows with hyperketonemia were used to analyze the status of autophagy and autophagy-related pathways AMP-activated kinase α (AMPKα) and mechanistic target of rapamycin (mTOR) in the mammary gland. The AMPKα and mTOR pathways were activated in the mammary glands of dairy cows with hyperketonemia compared with control cows. Furthermore, the autophagy activity was higher in the mammary glands of dairy cows with hyperketonemia. Our results contribute to our understanding of the response mechanism of the mammary gland to metabolic stress induced by hyperketonemia in peripartal dairy cows.
https://doi.org/10.3168/jds.2019-16910.
Pathogen-specific risk factors in acute outbreaks of respiratory disease in calves. By Pardon et al., page 2556. Respiratory tract infections are a major economic issue for the cattle industry and the leading cause of antimicrobial use in calves. This study used 7 individual polymerase chain reaction tests on pooled samples from the lower respiratory tract as an accessible tool for herd diagnostics to identify pathogen-specific risk factors in fall and winter outbreaks of respiratory disease. A virus was detected in 58.6% of the outbreaks, mostly bovine coronavirus. Mycoplasma bovis was found in 33.3%. Several pathogen-specific risk factors were identified, which might be useful for customizing control and prevention and better predicting the most likely pathogen before sampling results become available.
https://doi.org/10.3168/jds.2019-17486.
Validation of serum gamma-glutamyl transferase activity and body weight information for identifying dairy calves that are too young to be transported to auction markets in Canada. By Buczinski et al., page 2567. In this study, we aimed to predict the ability to detect dairy calves that were too young to be transported (<9 d old) to an auction market based on the new Canadian transportation rule when no birth date registry was available. We developed a model using body weight estimation and serum gamma-glutamyl transferase activity. The prediction accuracy was moderate at the calf level.
https://doi.org/10.3168/jds.2019-17601.
Ultrasonographic evaluation of umbilical structures in Holstein calves: A comparison between healthy calves and calves affected by umbilical disorders. By Guerri et al., page 2578. Umbilical disorders represent the third most frequent cause of disease in calves, leading to significant economic losses for farmers. Therefore, the practitioner should carefully assess each case for an umbilical disorder and implement an early therapeutic plan. The aim of this study was to evaluate the involution of umbilical structures during the first 4 wk of life, through the use of sonography and color Doppler evaluation, to help the practitioner detect umbilical disease before clinical signs of disease are present.
https://doi.org/10.3168/jds.2019-16737.
Effect of subclinical and clinical hypocalcemia and dietary cation-anion difference on rumination activity in periparturient dairy cows. By Goff et al., page 2591. Rumination monitoring systems help identify ill cows. Hypocalcemia, particularly clinical milk fever, reduces periparturient rumination activity. In this study, a prepartal diet with a low dietary cationanion difference improved blood calcium concentration in cows and increased the rate of rumination during the periparturient period.
https://doi.org/10.3168/jds.2019-17581.
Identifying gram-negative and gram-positive clinical mastitis using daily milk component and behavioral sensor data. By Steele et al., page 2602. Our study presents models derived from milk component and behavioral data for identifying any clinical mastitis (CM) case, CM caused by gram-negative bacteria or gram-positive bacteria, or CM cases with no pathogen isolated. Classification by causative pathogen type revealed some significant univariate indicators of CM and improved mastitis detection for gram-positive cases and cases in which no pathogen was isolated compared with all CM grouped together. On-farm sensor data may provide an additional screening tool for detecting mastitic cows.
https://doi.org/10.3168/jds.2019-16742.
Quantitative analysis of calf mortality in Great Britain. By Hyde et al., page 2615. The British national cattle register was used to analyze 21.2 million births and 21.6 million deaths registered between 2011 and 2018. A significant proportion of on-farm mortality occurred before 3 mo of age, and both dairy and male calves had higher mortality rates than beef and female calves, respectively. Month of birth and environmental temperature had a strong influence on mortality rate, and it appears that providing optimal environmental conditions would greatly reduce mortality rate. National cattle registers have great potential in monitoring mortality rates, and further research is needed to explore environmental factors likely to reduce calf mortality rates.
https://doi.org/10.3168/jds.2019-17383.
Efficacy of ketoprofen for treatment of spontaneous, culture-negative, mild cases of clinical mastitis: A randomized, controlled superiority trial. By Latosinski et al., page 2624. Many cases of clinical mastitis are culture-negative at microbiological examination of milk and do not require antimicrobial treatment. We tested the hypothesis that treatment of such cases with a nonsteroidal anti-inflammatory drug (ketoprofen) would reduce time to clinical cure, relapse, and recurrence of clinical mastitis; risk of subsequent intramammary infection; and milk somatic cell count. Considering the outcomes studied, our results indicated that treatment with ketoprofen was not effective.
https://doi.org/10.3168/jds.2019-17504.
Management of cull dairy cows: Culling decisions, duration of transport, and effect on cow condition. By Stojkov et al., page 2636. Cull dairy cows removed from 20 dairy farms in British Columbia were assessed at different locations throughout the transport continuum. On average, cows took more than 3 d from leaving the farm until arriving at a slaughter plant, usually via a livestock market. Many cows lost body condition, developed udder edema, and evinced reduced fitness for transport. When provided with information about management of cull dairy cows, farmers did not change their culling decisions. However, other factors, such as increased milk demand and the influence of herd veterinarians, appeared to affect farmers’ culling decisions.
https://doi.org/10.3168/jds.2019-17435.
Fitness for transport of cull dairy cows at livestock markets. By Stojkov et al., page 2650. As part of herd management, many cows with various health problems are removed from dairy farms and sold at livestock markets. In this study, about 30% of cows entering the market system had poor fitness for transport, including being thin or lame or having poor udder health or other defects. Increases in demand for milk influenced culling decisions and were associated with an increase in the percentage of compromised cows at the markets. At markets, cows with poor fitness for transport were sold for lower prices, particularly if they were thin or sick.
https://doi.org/10.3168/jds.2019-17454.
Short communication: Characterization of the milk protein expression profiles in dairy buffaloes with and without subclinical mastitis. By Tanamati et al., page 2677. Analysis of the milk proteomes of buffaloes with and without subclinical mastitis is important to improve our understanding of the alterations that occur in mammary tissues of animals with this disease. Comparison of these proteomes allows the identification of proteins that differ qualitatively and quantitatively in abundance in the milk of buffalo cows with and without mastitis and enables the identification of potential biomarkers for early detection of the disease.
https://doi.org/10.3168/jds.2019-16907.
Short communication: Characterization of Staphylococcus aureus from bulk tank milk of dairy cattle in Lombardy (northern Italy). By Gazzola et al., page 2685. Staphylococcus aureus is one of the most important pathogens causing mastitis in cattle. The aim of this study was to characterize Staph. aureus strains isolated from bulk tank milk of northern Italian dairy farms using ribosomal spacer polymer chain reaction. Additionally, a selection of the strains was analyzed using multilocus sequence typing and a gene-specific adlb polymer chain reaction. The applied methods aimed at evaluating the association between the Staph. aureus genotype and both the Staph. Aureus count and the somatic cell count in the samples of origin of the strains, thus predicting the clinical properties of isolates.
https://doi.org/10.3168/jds.2019-17181.
Short communication: Upper critical temperature-humidity index for dairy calves based on physiological stress variables. By Kovács et al., page 2707. In this study, we estimated the upper critical temperature–humidity index (THI) values for dairy calves based on noninvasive physiological indicators of heat stress (i.e., respiratory rate, heart rate, ear temperature, rectal temperature, and salivary cortisol concentrations). Sixteen calves were monitored for a 4-d period during summer. Our results suggest that the welfare of young calves may be compromised above a THI of 78 (increased respiratory rate and heart rate) and that calves experience significant heat stress above a THI of 88, as indicated by rectal temperature and salivary cortisol concentrations.
https://doi.org/10.3168/jds.2019-17459.
Technical note: Comparative evaluation of 3 methods for the quantification of nonesterified fatty acids in bovine plasma sampled prepartum. By Abuelo et al., page 2711. The quantification of nonesterified fatty acids (NEFA) in plasma is a useful tool for monitoring energy deficit during the late dry period and the onset of lactation. However, this approach requires the submission of samples to specialized laboratories, at significant cost. We compared the quantification of NEFA in 147 plasma samples for the gold standard diagnostic laboratory method and 2 alternative methods: a 96-well plate protocol and a small-scale analyzer. The alternative methods yielded results comparable with the gold standard. Also, both methods exhibited very good ability to detect excessive energy deficit precalving. These methods are suitable for quantifying NEFA for monitoring or research at a lower cost per sample.
https://doi.org/10.3168/jds.2019-17527.
Effect of 2-hydroxy-4-(methylthio) butanoate (HMTBa) supplementation on rumen bacterial populations in dairy cows when exposed to diets with risk for milk fat depression. By Pitta et al., page 2718. Diet-induced milk fat depression is an economic problem in dairy cows where a reduction in milk fat yield is observed as a result of the cow’s diet. 2-Hydroxy-4-(methylthio) butanoate (HMTBa) is a product that has been shown to prevent this condition, but the mechanism behind this is not understood. In this study, feeding a diet that increases the risk for milk fat depression was shown to alter the ruminal microbiome, and HMTBa was shown to prevent these alterations. This study provides new information on the role of rumen microbes in biohydrogenation pathways in the rumen and their consequent influence on milk fatty acid profiles in dairy cows.
https://doi.org/10.3168/jds.2019-17389.
Intravaginal instillation of prostaglandin F2α was as effective as intramuscular injection for induction of luteal regression in lactating dairy cows. By Masello et al., page 2743. In a randomized controlled experiment, we evaluated luteal regression risk, circulating progesterone levels, and reproductive outcomes in lactating dairy cows that received prostaglandin F2α (PGF2α) through intravaginal instillation or intramuscular injection. Despite minor differences in circulating progesterone concentration dynamics, intravaginal instillation of PGF2α resulted in similar luteal regression risk, proportion of cows detected in estrus, ovulation risk after induction of ovulation with GnRH, and pregnancy per artificial insemination after timed artificial insemination. Intravaginal instillation of PGF2α may be an alternative route of administration compared with intramuscular injection.
https://doi.org/10.3168/jds.2019-17589.
Use of glycerol and propylene glycol as additives in heat-treated goat colostrum. By MoralesdelaNuez et al., page 2756. Eleven goat colostrum samples with different added amounts of glycerol or propylene glycol were heat treated at 56°C for 1 h. In this study, both glycerol and propylene glycol added to heat-treated colostrum at 10 or 14% reduced aerobic mesophilic bacteria counts compared with control heat-treated colostrum. Glycerol and propylene glycol did not affect immunoglobulin G concentration in colostrum. However, propylene glycol at 14% decreased immunoglobulin M and immunoglobulin A concentrations and chitotriosidase activity. Based on these results, glycerol addition to goat colostrum before heat treatment could be recommended as an alternative to sanitize colostrum. However, propylene glycol addition was considered unsuitable.
https://doi.org/10.3168/jds.2019-17535.
Physiological effects of starter-induced ruminal acidosis in calves before, during, and after weaning. By Gelsinger et al., page 2762. It is unclear whether low rumen pH causes similar physiological dysfunction in calves as it does in adult cattle. Starter diets were developed to induce or blunt ruminal acidosis. Intake, body weight gain, feeding rate, blood parameters, rumen environment, and structural parameters were monitored as indicators of calf health. The calves in this study experienced ruminal acidosis symptoms similar to adult cattle, diet affected these responses, and the etiology of the disease seemed to follow similar mechanisms.
https://doi.org/10.3168/jds.2019-17494.
Body composition changes of crossbred Holstein × Gyr cows and conceptus during pregnancy. By Sguizzato et al., page 2773. Pregnancy is an important phase full of changes that animals undergo during their reproductive life. However, there is a shortage of studies evaluating how these changes occur. This study aimed to evaluate changes in maternal body composition and fetus development during different days of pregnancy when animals were fed 2 feed regimens: ad libitum or maintenance. Feeding regimen had no effect on changes in conceptus. Nevertheless, days of pregnancy plays an important role in development of conceptus and some changes in cows’ tissue and mammary gland composition.
https://doi.org/10.3168/jds.2019-17490.
Exposure to chronic light–dark phase shifts during the prepartum nonlactating period attenuates circadian rhythms, decreases blood glucose, and increases milk yield in the subsequent lactation. By Suarez-Trujillo et al., page 2784. Marked changes in metabolism occur during the transition from pregnancy to lactation. The circadian timing system is highly integrated with metabolic processes. Studying the effect of circadian disruption in preparturient dairy cows will enable a better understanding of the role of the circadian timing system in the metabolic adaptations to the onset of lactation. In the present study, circadian disruption in the prepartum period attenuated circadian rhythms and was associated with increased milk yield in the postpartum period. Results from this study suggest that the lower daily variations in the circadian rhythms may result in increased milk production.
https://doi.org/10.3168/jds.2019-16980.
Effects of rumen-protected methionine on lactation performance and physiological variables during a heat stress challenge in lactating Holstein cows. By Pate et al., page 2800. Heat stress can have vastly negative effects on dairy cattle physiology and lactation performance, causing extensive economic burden. In this experiment a heat stress challenge caused alterations to physiological parameters and behavior in dairy cattle, whereas rumen-protected methionine did not alter physiological parameters or behavior during heat stress. Dry matter intake, milk yield, or feed efficiencies were not affected by rumen-protected methionine feeding. However, when cows were fed rumen-protected methionine during a heat stress challenge, milk composition was positively affected.
https://doi.org/10.3168/jds.2019-17305.
Localization of aquaporin-3 proteins in the bovine rumen. By Zhong et al., page 2814. Transfer of urea into the rumen is of physiological and nutritional significance to ruminants. Aquaporin-3 proteins are potentially one of the mechanisms mediating urea transport across the rumen wall, but their exact location in the rumen is unknown. In this study, we detected multiple aquaporin-3 proteins of 25, 32, and 42 to 45 kDa in the cow rumen. These proteins were located throughout all cell layers of the rumen wall, especially in the innermost layer, suggesting that they may play a key physiological role in rumen function.
https://doi.org/10.3168/jds.2019-17735.
Hypoxia induces an increase in intestinal permeability and pulmonary arterial pressures in neonatal Holstein calves despite feeding the flavonoid rutin. By Shellenberger et al., page 2821. The effects of a 2-wk exposure to dietary rutin and environmental hypoxia on intestinal permeability and susceptibility to pulmonary arterial hypertension were evaluated in neonatal Holstein calves. Hypoxia deleteriously increased intestinal permeability and pulmonary arterial pressure. Rutin tended to be protective of pulmonary arterial pressure under hypoxic conditions, but it had no effect on intestinal permeability and appeared to worsen pulmonary arteriolar remodeling. The findings of this study implicate hypoxemia as a contributing cause of impaired gastrointestinal barrier function in neonatal calves and the associated deleterious health effects thereof.
https://doi.org/10.3168/jds.2019-17289.
Proteasome activity and expression of mammalian target of rapamycin signaling factors in skeletal muscle of dairy cows supplemented with conjugated linoleic acids during early lactation. By Yang et al., page 2829. Given possible positive effects of conjugated linoleic acids on muscle mass in humans and laboratory animals, we tested how dietary supplementation with these compounds during early lactation affected the regulation of specific signaling components involved in protein synthesis and degradation in skeletal muscle of dairy cows. We observed increased mRNA abundance of atrogin-1, a gene that is related to stimulation of protein degradation in muscle. We also observed increased abundance of mammalian target of rapamycin–associated signaling factors, a major regulator of protein synthesis, which might be a feedback mechanism to prevent excessive muscle protein degradation in these cows.
https://doi.org/10.3168/jds.2019-17244.
Branched-chain amino acids: Abundance of their transporters and metabolizing enzymes in adipose tissue, skeletal muscle, and liver of dairy cows at high or normal body condition. By Webb et al., page 2847. Branched-chain amino acid (BCAA) metabolism has been linked to obesity in mammals. The effect of calving body condition score (BCS) on the plasma BCAA concentrations and the abundance of BCAA transporters and degrading enzymes in adipose tissue, muscle, and liver of dairy cows during late pregnancy and early lactation was characterized. Our results indicate that over-conditioned animals (BCS >3.75) showed a greater decrease of circulating BCAA than normal-conditioned cows (BCS <3.5) around parturition. Further, adipose tissue may be a major site of BCAA uptake and initial degradation that is, however, not influenced by body condition.
https://doi.org/10.3168/jds.2019-17147.
Effects of n-3 fatty acids on growth, antioxidant status, and immunity of preweaned dairy calves. By Śpitalniak-Bajerska et al., page 2864. The study aimed to estimate the influences of flax oil and a mixture of esters of polyunsaturated fatty acids from flax oil added to a milk replacer formulation on the biochemical, immunological, and antioxidant status of blood, production parameters, and health of calves. Twenty-seven Holstein-Friesian calves were assigned to 3 groups: the control group, a group receiving ethyl esters of flax oil with lyophilized apples, or a group receiving flax oil with lyophilized apples. The preparations used for calf feeding beneficially affected production and physiological parameters. Our data support the idea that supplementation with n-3 fatty acids improves calf growth and metabolic and oxidative functions in young calves.
https://doi.org/10.3168/jds.2019-17001.
Short communication: Increasing temperature and pH can facilitate reductions of cephapirin and antibiotic resistance genes in dairy manure slurries. By Li et al., page 2877. Quantifying the fate of antibiotics and antibiotic resistance genes exposed to various temperatures and pH adjustments in manure slurries will help guide manure management practices to minimize the emergence and subsequent spreading of antimicrobial resistance. In the current study, effects of temperature and initial pH shock on cephapirin and antibiotic resistance genes in dairy manure slurries were investigated using a microcosm setup. Our results suggest that a change in temperature or initial pH adjustment during storage of dairy manure slurries could mitigate the spread of resistance.
https://doi.org/10.3168/jds.2019-17453.
Cross-sectional study of the effect of diet composition on plasma folate and vitamin B12 concentrations in Holstein cows in the United States and Canada. By Duplessis et al., page 2883. This cross-sectional study highlighted regional differences in North America for plasma folate and vitamin B12 concentrations in lactating dairy cows. Among the factors explaining the variations were parity and days in milk. We noted a negative relationship between plasma concentrations of folates and dietary fiber concentrations (neutral and acid detergent fibers and lignin) but a positive relationship between plasma concentrations of folates and dietary nonfiber carbohydrates. We observed the opposite trend for plasma vitamin B12 concentrations.
https://doi.org/10.3168/jds.2019-17657.
A virtual dairy herd as a tool to teach dairy production and management. By Calsamiglia et al., page 2896. A web-based virtual dairy herd was developed as a tool to teach introductory courses in animal and veterinary sciences. The tool can generate an unlimited number of herds to let students independently control daily activities. Immediate feedback helps students identify incorrect decisions, and automatic scoring allows its use in large classrooms. Students’ performance and evaluations indicate that the virtual dairy herd facilitated learning and understanding of dairy production in a motivating and integrated way.
https://doi.org/10.3168/jds.2019-16714.
Symposium review: Recent advances in dairy food safety research—An overview of the National Dairy Council Listeria Consortium, industry identification, and funding of research gaps. By Stubbs and Galer, page 2906. The food safety program of the Innovation Center for US Dairy is committed to providing science-based tools that help companies ensure that food safety is one of their highest priorities and deeply ingrained in their practices and corporate culture. This synopsis reviews a symposium on recent advances in dairy food safety research held at the ADSA annual meeting to help drive awareness of new tools that could help the industry improve the control of pathogens.
https://doi.org/10.3168/jds.2019-17337.
Symposium review: Transition cow calcium homeostasis—Health effects of hypocalcemia and strategies for prevention. By Wilkens et al., page 2909. Strict regulation of blood Ca concentration is necessary due to the various critical roles of Ca in the endocrine, immune, muscle, nervous, and skeletal systems. Dairy cows are prone to hypocalcemia because of the sudden demand of Ca for milk upon initiation of lactation. Although research efforts have largely minimized clinical hypocalcemia, subclinical hypocalcemia remains prevalent and has profound consequences for health and productivity of cows. This review addresses the relevance of hypocalcemia, the physiological mechanisms necessary to maintain normocalcemia, endogenous regulation of Ca homeostasis, and different approaches to improve Ca status in light of their modes of action.
https://doi.org/10.3168/jds.2019-17268.
Symposium review: Determinants of milk production—Understanding population dynamics in the bovine mammary epithelium. By Capuco and Choudhary, page 2928. A decline in the number of mammary secretory cells accounts for declining milk production with advancing lactation in cows. Terminating milking during the final months of pregnancy induces changes in gene expression, leading to mammary growth and extensive cell renewal. Replacement of senescent cells during lactation and the dry period is important for maintaining mammary gland functionality. Mammary stem cells and progenitors provide for cell renewal, mammary development, and tissue repair. We increased the number of these cells by infusing a normal metabolite through the teat. Similar treatments may provide means to enhance udder health and production efficiency.