Journal of Dairy Science最新文献

This review aimed to assess the scope of the literature on tracking the microbial community of biofilms, focusing on the dairy farm and processing environments. The majority of studies focused on either production, storage, transport or processing of milk, while 5 combined the investigation of both production and processing facilities. Factors influencing short-term changes in dairy microbiota such as the occurrence of mastitis and season were distinguished from factors revealed through long-term studies, such as feed and weather, rather than the milking equipment. Knowledge gaps were identified in relation to the study design, methods, data analysis and interpretation. The application of DNA sequencing technologies is particularly challenging with respect to samples with low microbial load (milk, swabs). There are few studies on the microbial composition of in situ biofilms, which might require new technologies for detection before sampling. Fundamental studies on the structure of biofilms are needed to identify the on-farm practices impacting the cycle of biofilm development in milking systems.

Pair housing presents an alternative to individual or larger group housing systems, though the effects of different pairing ages on calf welfare are not well understood. In this study, we examined the impact of pairing age on the performance, health, and behavior of dairy calves. A total of 140 Holstein female calves (n = 70 pairs) were used, paired at 3 ages: Early (6-7 d; 48 calves), Intermediate (29-30 d; 48 calves), and Late pairing (49-50 d; 44 calves). Calves were housed individually before pairing and weaned at 78 ± 2 d of age. Weight measurements were recorded at birth, 30, 50, 60 d, and at weaning. Calves' behavior was assessed 5 times per week through scan sampling after milk feedings from d 6-7 until weaning, and a food neophobia test was conducted at 50-51 d. Health assessments were performed 3 times per week by a veterinarian using Wisconsin clinical scores to diagnose diarrhea and BRD, with pulmonary ultrasonography at 55 d. The results suggest no association between pairing age and the prevalence of diarrhea or bovine respiratory disease (BRD), although our statistical power was limited. The number of calves with lung consolidation scores above 2 was also unaffected by pairing age. Early paired calves exhibited more exploration and play behaviors, and less idleness, stereotypies, and non-nutritive oral behaviors than Late paired calves. No differences were observed in cross-suckling likelihood across pairing ages. Early paired calves also showed a shorter latency to touch a novel feed in the food neophobia test, higher calf starter intake during the first 15 d, and greater ADG up to 50 d. Although overall ADG did not differ among pairing ages, Early paired calves were more homogeneous in weaning weight compared with Late paired calves. In conclusion, early pairing supports calves' initial development, promoting early feeding behavior and growth, enhancing behaviors associated with positive affective states, and without adverse effects on health or undesirable behaviors.

Newborn calves face challenges adapting from the warm uterine environment to cold ambient temperatures, often experiencing cold stress. The objective of this study was to assess the preferred inside hutch temperature of dairy calves in their first week after birth during Central European winter and to compare lying behavior in heated and non-heated hutches. Sixteen matched pairs of dairy calves (2.6 ± 1.3 d old) were enrolled in 7d replicates with a preference and a control phase. During preference phase the calf could choose between 4 different hutches with access to a shared paddock. Inside the hutches either 0, 1, 2 or 3 heat lamps (HL0, HL1, HL2, HL3) were switched on. The control calf was kept in a non-heated hutch with an enclosed paddock. Calves were observed for 3 to 4 d, then switched from preference to control phase (or vice versa) and observed again for 3 to 4 d. Location of calves was documented once per minute by a time-lapse camera. Lying times and lying bouts were monitored by a 3D accelerometer data logger attached to the calves' metacarpus. With each additional heat lamp switched on, the temperature inside the hutches rose by 2.6 ± 1.0°C. Calves spent 90% of their time inside a hutch, irrespective of the number of heat lamps switched on. No preference for a specific inside hutch temperature existed. There was, however, a tendency for the location of the hutches closest to the control calf. Lying behavior did not differ between preference and control phase, but decreased marginally with increasing age. These findings could indicate that there is a need of shelter for calves in winter, but without a preference for a certain inside hutch temperature under the prevailing conditions of deep straw bedding, highly sufficient milk supply and an ambient temperature of 5.4 ± 3.3°C.

This study investigated the genetics of bovine tuberculosis (bTB) infectivity in Holstein-Friesian dairy cows using British national data. The analyses included cows with recorded sires from herds affected by bTB outbreaks between 2000 and 2022. Animals were considered bTB-positive if they reacted positively to the skin test and/or had positive post-mortem findings. We introduced the "index case approach," based on the assumption that once the initial positively tested animals (index cases) are detected in a herd, subsequent infections (secondary cases) in the early stages of the breakdown are likely to be attributed to these animals. Genetic analysis of the number of secondary cases (NSC) associated with a given index case was used to establish evidence of genetic variability in bTB infectivity of cattle, and derive Estimated Breeding Values (EBVs) for infectivity for the sires of the index cases. Data were analyzed by employing Markov Chain Monte Carlo techniques to fit Generalized Linear Mixed Models with either Poisson, Zero-Inflated Poisson (ZIP), Hurdle Poisson, or Geometric distributions. All 4 models demonstrated presence of genetic variance in cattle infectivity, with the strongest evidence provided by the ZIP and Hurdle Poisson models. The Hurdle Poisson model offered the most accurate and least biased predictions. Sire infectivity EBVs from the Poisson, ZIP, and Geometric models showed strong concordance, with pairwise correlations of 0.90 or higher. In contrast, correlations between EBVs from the Hurdle Poisson model and the other models ranged from 0.36 to 0.39. The association of the sire infectivity EBVs with the average observed NSC per sire and the proportion of infectious index case daughters per sire was generally moderate with correlations between 44 and 47% and 65-69%, respectively. Agreement among models for identifying the genetically most infectious sires was also reasonable, with 151 out of 285 sires appearing in the top 10% across models, and 122 (42.8%) also aligning with the top 10% based on observed average NSC. Results provide novel evidence for exploitable genetic variance in bTB infectivity allowing the derivation of meaningful EBVs. Based on the estimated posterior mean genetic variances obtained, reduction in infectivity by one genetic standard deviation would result in a 32% - 44% decrease in the expected NSC per index case. Further research is warranted to refine the phenotypic definition of infectivity and assess correlation with other dairy traits.

Whey protein phospholipid concentrate (WPPC) is a co-product generated during the manufacture of whey protein isolate. WPPC is depleted of simple sugars but contains numerous glycoconjugates embedded in the milk fat globule membrane, suggesting this fraction may serve as a carbon source for growth of bifidobacteria commonly enriched in breast fed infants. In this work, we demonstrate that WPPC can serve as a sole carbon source for the growth of Bifidobacterium bifidum, a species common to the breastfed infant and routinely used as a probiotic. Growth on WPPC fractions resulted in expression of key extracellular glycosyl hydrolases in B. bifidum associated with the catabolism of glycoproteins. Interestingly, this included induction of fucosidase genes in B. bifidum linked to catabolism of fucosylated human milk oligosaccharides even though the WPPC glycan possesses little fucose. Additional growth studies revealed that WPPC-glycan components N-acetylglucosamine or N-acetylgalactosamine were required for pre-activation of B. bifidum toward rapid growth on the fucosylated human milk oligosaccharides. Growth on WPPC fractions also resulted in expression of extracellular sialidases in B. bifidum which promoted a consistent release of sialic acid, a well-known component of bovine milk oligosaccharides and glycoconjugates with potential impacts on gut microbial ecology and host cognition. These studies suggest WPPC may serve as a promising bioactive component to facilitate probiotic activity for use in infant formulas and other synbiotic applications.

The aims of this study were to assess the effect of meloxicam at the time of lameness treatment for hoof-horn (HH) lesions in dairy cattle on 1) time to lameness soundness post trimming and block application and 2) reproductive success Five seasonal-calving pasture-based dairy farms located in the Waikato region of New Zealand were enrolled into a randomized clinical interventional trial. Farmers were tasked with identifying lame animals over a period of approximately -4 to 6 weeks relative to the herd start of mating (HSM), with lameness subsequently confirmed with lameness score (LS) by trained technicians (0-3 scale, where ≥2 are considered lame). Animals with a LS ≥2 were examined by a veterinarian who then enrolled animals if they presented lame with HH (white-line or sole) lesions. This same veterinarian then provided therapeutic hoof trimming, and application of wooden blocks, to the enrolled lame animals. Randomization into either meloxicam (0.5 mg/kg sub-cutaneous) or negative control groups was conducted after trimming, with animals blocked by farm and lesion. Following lameness treatment, animals were lameness scored at a median interval of every 4 d until sound (LS = 0), with scoring occurring regardless of block retention status; blocks were not removed at any stage. Animals had conception date and pregnancy status confirmed via rectal ultrasound. Outcomes were number of days to soundness (animals may still have block on) and number of days from HSM to conception, and binary outcomes of pregnant within 6 weeks of the breeding period and final pregnancy status. Cox proportional hazard methods were used to analyze the time-to-event outcomes, with binary outcomes analyzed using multivariable logistic regression methods. A total of 241 animals were enrolled, 123 into the meloxicam group and 118 into the control group. The majority of lesions were described as white-line (225; 93%), with 207 (86%) animals receiving wooden blocks on the non-lame hoof. No improvement in the time to soundness was reported between animals in the 2 treatment groups (hazard ratio 0.78; 95% CI 0.56 - 1.03 for meloxicam treated animals compared with control animals), with most scoring events occurring with a block present. From the 229 animals with reproductive outcome data (117 meloxicam treated and 112 control treated), the hazards of conception in meloxicam treated animals were 1.42 (95% CI 1.06 - 1.90) times that for the control animals. Meloxicam treated lame animals had 15% greater predicted probabilities of conceiving within the first 6 weeks of the breeding period (P = 0.037) and final pregnancy status (P = 0.019), respectively, compared with control lame animals. The addition of meloxicam to the treatment regimen of lame dairy cattle with HH lesions can significantly improve reproductive outcomes, despite no apparent difference in time to soundness.

Diet-induced milk fat depression (MFD) caused by UFA, and low fiber diets results in an increase in alternate rumen biohydrogenation intermediates. The impact of these MFD-inducing diets on milk odd and branched chain fatty acids (OBCFA) is not well known. The first objective of this study was to characterize the time course of changes in OBCFA in milk fat during induction and recovery of MFD induced with a high UFA and low fiber diet in 3 separate experiments. In the first experiment, milk OBCFA were quantified in a previous experiment that sampled milk fat every other day during induction and recovery of MFD. Induction of MFD decreased all OBCFA in milk fat except iso 17:0, which was increased by 15%. The temporal response varied between OBCFA, with iso 15:0, anteiso 15:0, 17:0, anteiso 17:0, ∑ ante, and ∑ OBCFA progressively decreased after the first day, while iso 14:0, iso 16:0, and ∑ iso decreased after d 5. The OBCFA were progressively increased during recovery, and most were similar to the control by d 3. Two additional experiments investigated the change in milk OBCFA during recovery from MFD with diets that differed in UFA, fiber, or monensin supplementation. The effect of MFD on milk OBCFA was similar to Experiment 1 and the temporal response during recovery was similar to recovery of normal rumen fermentation. The second objective was to characterize the response across MFD experiments conducted in our research group. The database included 7 experiments that fed either a control diet or a diet that caused MFD through either a change in fiber, UFA, or both. The MFD diet decreased most OBCFA in milk fat, including iso 14:0, 15:0, iso 15:0, anteiso 15:0, iso 16:0, 17:0, anteiso 17:0, ∑ iso FA, ∑ anteiso FA, ∑ OBCFA. However, iso 17:0 and cis-9 17:1 were not different between control and MFD diets. In conclusion, milk OBCFA other than iso 17:0 and cis-9 17:1 are reduced when feeding a diet that causes Biohydrogenation-induced MFD and the temporal response was similar to the alternate rumen biohydrogenation intermediates and likely indicates the time course of adaptation of rumen microbial populations and fermentation during these diet alterations.

The nutritional value of any food product has historically been measured by the calorific value of individual components, harking back to the days of the development of the bomb calorimeter. A fuller understanding of nutrition later took into account the need for specific components, such as proteins, carbohydrates, vitamins and minerals, that ere known to be required for good human health and growth. In milk and milk products, these include casein and whey proteins, lactose, milk fat triacylglycerides, minor lipid components (both charged and neutral), calcium, and micronutrients. Whey proteins are known to be richer in essential amino acids, compared with casein, and also to contain branched chain amino acids for muscle growth. Calcium is found in the form of the calcium phosphate mineral and is dispersed, but largely insoluble in milk. All of this information does not take into account interactions between milk components, and therefore can be considered as a reductionist nutritional approach. This review takes a structural and physical chemical approach to understand how digestibility and nutritional delivery is impacted by microstructures and nutrient component interactions, with a focus on mechanistic explanations.