Journal of Dairy Science最新文献

The objective of this study was to assess the potential benefit of a single-step GBLUP (ssGBLUP) genomic prediction approach to subclinical mastitis (SCM) and SCS traits in the early first lactation of heifers. Subclinical mastitis is highly prevalent during early lactation and poses significant challenges to both animal welfare and farm profitability. Given the low h² of SCM, ssGBLUP has emerged as an effective approach for the genomic prediction of such low-h² traits. This approach combines phenotypic data and genomic and pedigree information simultaneously through a hybrid relationship matrix to predict GEBV. In this study, accuracy and bias of GEBV for SCM (defined in 6 alternative ways) and SCS were assessed using the ssGBLUP approach in Canadian Holstein heifers early in their first lactation. A reference dataset, consisting of a large random sample of 544,221 heifers from 3,021 herds, containing records up to 2021, was truncated to create another dataset with records up to 2016, which were used for breeding value estimation and validation, while a smaller random sample of 137,518 heifers from 755 herds was used for genetic parameter estimation. Validation reliability and prediction bias of GEBV were estimated using ssGBLUP and were compared with the EBV derived from traditional BLUP. For constructing the hybrid relationship matrix used in the ssGBLUP, various scaling factors were tested for combining genomic and pedigree relationships. The incidence of 6 SCM trait definitions within 5 to 30 DIM ranged from 15.32% to 24.71%. Heritability was 0.047 to 0.069 for 6 SCM traits and 0.102 for SCS. Application of the ssGBLUP model substantially increased validation reliabilities of GEBV of young animals, with average gains of 0.28 (SCM traits) and 0.19 (SCS) points with optimal scaling factors. Furthermore, in comparison to EBVs obtained with a traditional BLUP method, the ssGBLUP model had slightly reduced bias in GEBV (overall with various scaling factors). Moreover, in terms of average theoretical reliabilities, gains of 0.22 and 0.27 and 0.20 and 0.28 were observed, respectively, for reference and truncated datasets of SCM traits and SCS, respectively. We concluded that ssGBLUP produced GEBV with increased reliability and less bias for young animals compared with EBV from a conventional BLUP approach. Hence, implementation of ssGBLUP in routine evaluation of SCM should be further considered within the context of the Canadian dairy industry.

This meta-analysis evaluated the effects of tannin-based feed additives on enteric methane (CH₄) emissions, nutrient digestibility, and animal performance in beef and dairy cattle. A total of 23 peer-reviewed studies comprising 75 treatment means were included in the analysis. Random effects and mixed effects models were used to estimate relative mean differences and identify moderators of response. Robust variance estimation accounted for within-study dependence. Overall, tannin supplementation significantly reduced enteric CH₄ emissions (-10.2%) and CH₄ yield (-9.3%) across studies in beef and dairy cattle. Although no significant differences were detected between cattle types for CH₄ emissions or yield, the database was unbalanced (14 beef vs. 9 dairy studies), and statistical support for a reduction in lactating dairy cows (7 studies) was weaker when analyzed separately (df = 1.7). These results warrant cautious interpretation for dairy systems. Likewise, no interactions between cattle type and tannin dose were detected for CH₄ emissions or yield. The incomplete factorial representation of tannin types across cattle types further limited the evaluation of potential tannin type × cattle type interactions. No interaction between tannin type and dose was observed for enteric CH₄ emissions or yield. Methane intensity in dairy (g/kg ECM) and beef cattle (g/kg average daily gain) was not affected by tannin supplementation, mainly due to differences in performance responses across studies. In dairy cattle, tannins had no significant effect on DM intake, milk yield, or milk composition. In beef cattle, tannins significantly decreased fiber digestibility by 9.8%, which was associated with reductions in enteric CH₄ emissions. Ruminal fermentation parameters and pH were unaffected in both dairy and beef cattle. Meta-regression indicated that CH₄ yield decreased by 1.0% per 1 g/kg DM increase in tannin dose. Effective mitigation generally required inclusion rates above ∼8,000 to 10,000 mg/kg DM, whereas subtherapeutic levels (<1,000 mg/kg DM) were often ineffective or even associated with increased emissions. Overall, standardized condensed tannin additives appear to be a viable mitigation strategy, particularly in beef cattle, where evidence is strongest. In contrast, results for dairy systems remain limited and require confirmation through additional studies. Finally, between-study differences observed for enteric CH₄ emissions and yield highlight that the magnitude of tannin effects is likely driven more by bioactive properties than tannin type or dose. Future studies should quantify tannin bioactivity and evaluate its interaction with diet and rumen microbiota to enhance mitigation strategies.

Early weaning disrupts gut microbiota homeostasis and increases oxidative stress and inflammation in calves, thus negatively affecting their growth performance and health. Resveratrol is a polyphenol with antioxidant and anti-inflammatory properties that modulates gut microbiota and metabolites. In the present study, we investigated the effects of resveratrol on growth performance, immune function, antioxidant capacity, gut microbiota, and metabolic pathways in early-weaning calves. Thirty-six newborn Simmental × Holstein F₁ generation female calves were randomly assigned to one of 3 treatment groups: conventional weaning at 63 d of age (CON), early weaning at 49 d of age (EW), or early weaning at 49 d of age with 2 g/d resveratrol supplementation from d 7 to d 49 (EWR). The results revealed that the final BW, ADG, and feed efficiency were greater in the EWR group than in the CON group, and diarrhea incidence was significantly reduced. The EWR treatment decreased the concentrations of the proinflammatory cytokine IL-1β and the oxidative damage product malondialdehyde. Meanwhile, resveratrol supplementation increased the anti-inflammatory cytokine IL-4, catalase, and the total antioxidant capacity in early-weaning calves, which were not significantly different from CON group. In addition, EWR increased the abundance of Parabacteroides, Eubacterium_coprostanoligenes_group, Christensenella, and Ruminococcaceae, as well as increased concentration of butyric acid, valeric acid, isobutyric acid, isovaleric acid, and total branched short-chain fatty acids. Metabolomic analysis revealed that resveratrol significantly enhanced the tryptophan metabolic pathway. Correlation analysis suggested that Parabacteroides was closely related to the modulatory effects of resveratrol in early-weaning calves through its involvement in tryptophan metabolism. In conclusion, dietary resveratrol supplementation improves growth performance and reduces diarrhea in early-weaning calves by alleviating inflammation and oxidative stress, modulating gut microbiota, and enhancing microbial tryptophan metabolism.

Gestation induces strong anatomical, histological and transcriptomic changes in the pregnant female brain. Our study aimed to characterize the RNA transcripts expressed in the goat brain and their main structural, transcriptional, and functional features, while also exploring whether 2-mo (57 d) pregnancy affects transcript usage in the brain. Twelve brain tissue samples from three 2-mo pregnant and 4 nonpregnant Murciano-Granadina goats were sequenced. A total of 62,185 transcripts from 29,044 genes (averaging ∼2.14 transcripts per gene) were detected, and ∼60% of them were novel transcripts or novel loci. Transcript usage in the brain tissues of pregnant goats revealed widespread changes in alternative splicing. A total of 2004 genes (18.14% of all expressed multitranscript genes) exhibited significant shifts in transcript usage in response to 2-mo pregnancy. The hippocampus displayed the most substantial changes, with 689 differentially used transcripts from 545 genes. Other tissues showing notable shifts were the pineal gland (374 transcripts), the olfactory bulb (301 transcripts), and the adenohypophysis (281 transcripts). In contrast, the pons showed a markedly lower level of differential transcript usage in response to pregnancy. These results evidence that the adaptive response of the brain to pregnancy is mediated not only by changes in gene expression, but also by the preferential use of specific gene isoforms.

This study aimed to determine the effect of supplementing milk replacer (MR) with increasing doses of a mixture of ethyl esters of polyunsaturated fatty acid of linseed oil (EEPUFALO; α-linolenic acid 55.5%, linoleic acid 13.3%, and oleic acid 18.0%) on growth performance, health, immune status, and oxidative stress parameters of preweaning dairy calves. A total of 54 Holstein-Friesian calves (5 d of age, 39.8 ± 0.69 kg, both males and females) were divided into 3 groups, each consisting of 18 animals: a control group and 2 treatment groups (D1 and D2), receiving 0, 15, and 30 mL/d of EEPUFALO incorporated into the MR, respectively. Each calf remained in the experiment from 5 to 56 d of age and had free access to starter mixture. Feed intake and fecal fluidity were monitored daily, body weight and body morphometric measurements were recorded weekly, and blood samples for hematological, immune status and oxidative stress parameters were collected on 14, 28, 42, and 56 d of age. Supplementation with increasing doses of EEPUFALO quadratically increased average daily MR and total DMI, with the highest in D2. Supplementation with EEPUFALO increased final BW and total BW gain in a quadratic manner, with the highest performance in group D2. Average daily gain and feed efficiency also followed a quadratic response, with the highest values in group D2. Supplementation with EEPUFALO had limited effects on hematological parameters, though it significantly reduced neutrophil percentage and increased lymphocyte concentration, particularly in the D2 group. We further found that EEPUFALO tended to lower serum haptoglobin levels and significantly decreased tumor necrosis factor-α concentrations, with linear response indicating the most pronounced effects in group D2. Although total oxidant status showed a numerical decrease, total antioxidant status increased significantly, especially in group D2, contributing to a tendency for reduced oxidative stress index. No significant changes were observed in serum superoxide dismutase activity and plasma malondialdehyde concentration. Supplementation with EEPUFALO improved calf health, as indicated by fewer days of veterinary care. In conclusion, supplementation of MR with EEPUFALO at a dose of 30 mL/d improved calf performance, potentially due to its beneficial effects on immune function and the reduction of oxidative stress.

The objectives of the study were to investigate changes in the number of selected groups of microorganisms and the level of antioxidant activity during storage of model unripened cheeses with the addition of dried nettle leaves, to compare their sensory characteristics, as well as to determine the antioxidant properties of the obtained whey. Three groups of model unripened rennet-curd cheeses were produced: I-a control sample without a plant additive, II and III-samples with the addition of dried nettle leaves in the amount of 0.165% and 0.330% (g/100 g of milk), respectively. Advantageously, no effects of nettle addition on total microbial and Lactococcus counts were determined. Moreover, the application of this herb slowed down the yeast and mold growth in cheese, increased the antioxidant activity, and elevated the contents of total polyphenols, caffeic acid, p-coumaric acid, rutin, and ferulic acid. Additionally, the antioxidant properties of the obtained whey were also higher in comparison to control. Sensory analysis revealed that the addition of a lower amount (0.165%) of dried nettle leaves appeared to be the most favorable option, balancing improved nutritional and antioxidant value with acceptable sensory characteristics and acceptability. The study demonstrated that the application of dried nettle leaves as an addition to cheese offers many benefits.

The typical objective of genomic analyses is to assess additive genetic variance in traits. However, the nonadditive component of genetic variation is often disregarded. Consequently, genomic analyses may not directly elucidate the complex genomic structures or other potential underlying mechanisms, such as pleiotropy, dominance, or epistatic effects. Furthermore, polygenic traits are likely to be subject to nonadditive interactions. Specifically regarding traits pertaining to fitness, including fertility, genomic regions exhibiting nonadditive genetic effects, potentially resulting from directional dominance or epistatic effects, have been identified and require further investigation. In this study, data from more than 7,400 German Holsteins dairy cows with continuous observations of their reproduction performance across the first 3 lactations were analyzed. In the first instance, variance component estimations for 12 observations, distributed across 4 different traits across the 3 lactations, were conducted. The results obtained confirmed low h² for all traits, with the lowest value, h² = 0.016, observed for stillbirth maternal in the third lactation and the highest being h² = 0.128 for metritis in the first lactation. Hereafter, GWAS were employed as an initial step to identify chromosomes of interest for each trait and lactation combination. Hereby, a total of 23 genomic regions were identified as significantly associated and subsequently investigated using a machine learning random forest (RF) approach to screen for putative further nonadditive regions of interest. The correlation (r) between repeated RF models exhibited a mean value of r = 0.854 to r = 0.973, while the average proportion of incorrectly predicted animals remained between 0.102 and 0.244. A direct comparison with the 35 significantly associated markers identified by GWAS revealed common markers, as well as the chromosome- and trait-specific architecture, which displayed different patterns of association signals across the complex of reproduction traits. Screening database records confirmed the identified markers in proximity to previously described genes in the context of reproduction as well as dairy cattle genomics. The findings of our study represent a contribution to a better understanding of the complexity of further nonadditive genetics underlying functional traits using GWAS results, with particular attention to regional clustering. Furthermore, they may serve as a foundation for regional in-depth analysis using a broader cohort of animals.

The multitude of environmental factors that affect health and production of dairy cows have been documented extensively in the literature. However, the influence of wildfire smoke on dairy production has only been investigated in recent years. Wildfires are becoming a greater source of air pollution across the United States, leading to public health concerns. Given the prevalence of dairy operations residing in fire-prone regions, wildfires may have an under-recognized role in suboptimal dairy production. Recently, investigators have found that air pollution from wildfires and nonwildfire sources induces health issues and reduces milk production in dairy cows and meat quality in beef cattle. These outcomes may emanate from stress and immune and metabolic perturbations. This review highlights the literature that has established the current state of knowledge regarding the effects of air pollutants, particularly those from wildfires, on the dairy industry. Evidence suggests that air quality is an important factor affecting production and health metrics in dairy cows and calves, and should be considered to enhance the health, performance, and welfare of dairy cattle.