Limits to sustained energy intake. XXXII. Hot again: dorsal shaving increases energy intake and milk output in golden hamsters (Mesocricetus auratus)

Golden hamsters have four times the body size of mice, raise very large litters and are required to produce large quantities of milk during the 18-day lactation period. We have previously proposed that they may be prone to being limited by their heat dissipation capacity. Studies where lactating females are shaved to elevate their heat dissipation capacity have yielded conflicting data so far. With their short pregnancy of ∼18 days, the large litters and the reported high skin temperatures, they may serve as an ideal model to elucidate the role of epilation for energy budgets in lactating mammals. We shaved one group of lactating females dorsally on the sixth day of lactation, and tested if the elevated heat dissipation capacity would enable them to have higher energy intakes and better food-to-milk conversion rates. Indeed, we observed that females from the shaved group had 6% higher body mass and 0.78°C lower skin temperature than control females during lactation. When focusing on the phase of peak lactation, we observed significantly higher (10%) gross energy intake of food and 23.4% more milk energy output in the shaved females, resulting in 3.3 g higher individual pup weights. We conclude that shaving off the females' fur, even though restricted to the dorsal surface, had large consequences on female energy metabolism in lactation and improved milk production and pup growth in line with our previous work on heat dissipation limitation. Our new data from golden hamsters confirm heat dissipation as a limiting factor for sustained metabolic rate in lactation in some small mammals and emphasise the large effects of a relatively small manipulation such as fur removal on energy metabolism of lactating females.

Requirements of milk intake and intake of milk components for pre-weaning growth of Pelibuey lambs

The objective of the present study was to determine the needs of milk intake (MI) and their components (i.e., lactose, fat, protein, and energy) to increase the average daily gain (ADG) of Pelibuey lambs during the pre-weaning period. Data of 62 lambs were used (35 males and 27 females; 32 of single lambing and 30 twins). All lambs were housed in individual pens with their mothers during the first 45 days post-lambing, without access to mother's food. Every 10 d, MI was estimated by the double lamb weighing method, and then, the intake of each milk component was calculated, considering both milk chemical composition and its estimated intake. The ADG was associated with MI and its components through a linear regression analysis. All milk variables were highly (P < 0.05; 0.69 ≤ r ≤ 0.85) correlated with ADG. The ADG explained (P < 0.0001) between 48 and 72% of the variation observed for MI and its components, being lower for fat intake and higher for MI. Given the positive slope parameter (β1), an increase of one kilogram of body weight required intakes of 3.1 kg of milk, 117 g of fat, 203 g of protein, 187 g of lactose, or 16.8 MJ of energy. In conclusion, Pelibuey lambs to gain one kilogram of live weight during the pre-weaning period need to consume 3.1 kg of milk having an adequate amount of protein, fat, lactose, and energy.

Productive and reproductive performance of females F1 Holstein x Gir daughters of proven bulls

Records of 234 lactations from F1 Holstein x Gyr daughters of proven bulls were used in this study for the evaluation of productive and reproductive characteristics of cows. Data were collected from a private farm located in the municipality of Santo Antônio do Monte, MG, Brazil. The objective of this study was to evaluate the effects of Holstein bull's PTA milk (predicted transmitting ability) calving year, season, and parity on the productive and reproductive characteristics of F! cows. The productive characteristics analyzed were total milk production (TMP), average daily production (ADP), days in milk (DIM), and milk yield per day of calving interval (MYDCI). The studied reproductive characteristics were service interval (SI), calving interval (CI), and gestation length (GL). The results were subjected to statistical analysis and means for significant effects were compared using Duncan's test at a significance level of 5%. F1 animals efficiently expressed their genetic potential for milk production with an average total milk production of 7842.61 kg and average daily production of 24.53 kg. Means for days in milk, milk yield per day of calving interval, service interval, calving interval, and gestation length were 322.52 days, 20.73 kg, 106.0 days, 383.23 days, and 276.18 days, respectively. Properly managed F1 Holstein x Gyr daughters of proven bulls fed a balanced diet efficiently expressed their genetic potential for milk production without adverse effects on reproduction. Moreover, Holstein x Gyr cows should be selected based on parents' PTA for milk traits and other factors such as environmental conditions and management.

Methylome and transcriptome profiles in three yak tissues revealed that DNA methylation and the transcription factor ZGPAT co-regulate milk production

Background

Domestic yaks play an indispensable role in sustaining the livelihood of Tibetans and other ethnic groups on the Qinghai-Tibetan Plateau (QTP), by providing milk and meat. They have evolved numerous physiological adaptations to high-altitude environment, including strong blood oxygen transportation capabilities and high metabolism. The roles of DNA methylation and gene expression in milk production and high-altitudes adaptation need further exploration.

Results

We performed genome-wide DNA methylome and transcriptome analyses of breast, lung, and biceps brachii muscle tissues from yaks of different ages. We identified 432,350 differentially methylated regions (DMRs) across the age groups within each tissue. The post-mature breast tissue had considerably more differentially methylated regions (155,957) than that from the three younger age groups. Hypomethylated genes with high expression levels might regulate milk production by influencing protein processing in the endoplasmic reticulum. According to weighted gene correlation network analysis, the “hub” gene ZGPAT was highly expressed in the post-mature breast tissue, indicating that it potentially regulates the transcription of 280 genes that influence protein synthesis, processing, and secretion. The tissue network analysis indicated that high expression of HIF1A regulates energy metabolism in the lung.

Conclusions

This study provides a basis for understanding the epigenetic mechanisms underlying milk production in yaks, and the results offer insight to breeding programs aimed at improving milk production.

Supplementary information

Supplementary information accompanies this paper at 10.1186/s12864-020-07151-3.

Effect of different roughage sources associated banana pseudostem hay on the nutritional and behavioral parameters and performance of F1 Holstein/Zebu lactation cows

The objective of this study was to evaluate the association of pseudostem hay of banana trees of different roughages in the diet of F1 Holstein/Zebu cows on their nutrient intake and digestibility, nitrogen balance, microbial synthesis, ingestive behavior, and milk production. The experiment was distributed in two simultaneous 4 × 4 Latin squares. The treatments were as follows: diet 1-sorghum silage as exclusive dietary roughage; diet 2-sorghum silage (70%) associated with 30% pseudostem hay of banana trees (dry matter basis); diet 3-70% elephant grass with 30% pseudostem hay of banana trees (dry matter basis); and diet 4-70% sugarcane with 30% banana pseudostem hay (dry matter basis). The roughage/concentrate ratio was 75:25. The animals fed with sorghum silage presented 14.45% higher intake (p = 0.01) to that of animals fed hay and elephant grass. The diets containing silage and silage with hay showed digestibility of neutral detergent fiber corrected for ash and protein that was 57.75% higher (p < 0.01) than that of other diets. Cows fed elephant grass spent more time intake (p = 0.01). Diets did not influence milk yield (p = 0.47), and the milk yield corrected for 3.5 fat (p = 0.22), final weight (p = 0.06), and intake efficiency (p = 0.57), presenting a mean of 14.16 kg/day, 15.94 kg/day, 590 kg, and 0.9 kg of milk/kg of ingested dry matter, respectively. The utilization of pseudostem hay associated with other roughage can be an alternative to milk yield in F1 Holstein/Zebu cows.

Predicting milk yield in Pelibuey ewes from the udder volume measurement with a simple method

In this research communication we describe the creation of an equation for the prediction of milk yield (MY) from udder volume (UV). A total of 280 measurements were collected between 5 and 15 d postpartum (pp) from 36 multiparous Pelibuey ewes. Study variables were measured between 2 and 9 weeks pp and MY was measured by manual milking, UV prior to and following milking was measured using the technique of making moulds from aluminium foil. The MY ranged from 0.09 to 0.83 kg/d, meanwhile UV prior and following milking ranged from 155 to 1940 and 90 to 1520 cm3, respectively. Measurements of UV had a moderate to high (P < 0.01; 0.58 ≤ r ≤ 0.78) correlation with MY. The UV prior to milking was the best prediction model for MY, which explained 62% of the variation in MY. This equation presented moderate precision (r2 = 0.61) and high accuracy (bias correction factor = 0.94), confirming a good reproducibility index (concordance correlation coefficient = 0.73). Modelling efficiency (MEF = 0.59) showed moderate concordance between observed and predicted values. In conclusion, MY in lactating Pelibuey ewes could be predicted in a moderate way using the predictor variable UV measured with the technique of moulds made with aluminium foil.

Selective flukicide treatment of non-lactating cows and the corresponding production impact of Fasciola hepatica in dairy herds in Sweden

A control strategy against Fasciola hepatica infection based on selective treatment of non-lactating animals was evaluated in four Swedish dairy herds. The study was conducted over the course of two consecutive seasons in moderately to highly F. hepatica infected herds with robotic milking, where heifers and dry cows received an oral drench with albendazole (10 mg/kg) during three visits in January, February and March in both 2017 and 2018. This resulted in an anthelmintic coverage between 38 % and 58 % of the animals. Furthermore, on each visit, the infection status of all dewormed animals along with 15 randomly selected milking cows were monitored by detection of F. hepatica coproantigens. Individual milk samples were also collected quarterly from the whole herds for measurements of individual antibody levels against the parasite using milk ELISA. In addition, individual data on milk yield and quality were collected on a monthly basis between 2016 and 2018. To further study the impact of the infection on milk production, truly F. hepatica positive and negative cows in the first lactation were identified based on the results from coproantigen and milk ELISA assays. Total F. hepatica coproantigen prevalence in the herds varied between 28 % and 85 % in the first year, and between 27 % and 68 % in the second year of the study. We found that two years of treatments resulted in a significant decrease of coproantigen-positivity especially on the two most heavily infected farms. These results were confirmed by a similar drop in within-herd prevalences obtained by milk ELISA results. The infection had a significant negative impact on milk yields in untreated F. hepatica positive cows. No consistent long-term effect was observed at the herd level probably due to the influx of animals infected before puberty and/or adult animals that were re-infected at dry-off. This is the first study of the effects of F. hepatica infection on milk yield and quality in dairy herds in Sweden.

Maternal chitosan oligosaccharide intervention optimizes the production performance and health status of gilts and their offspring

Chitosan oligosaccharides (COS) are the hydrolyzed product of chitosan and have multifunctional health benefits. The objective of this study was to elucidate the effect of COS as a dietary supplement to gilts on their productivity and health and that of their litters. Gilts were randomly assigned to either a treatment (n = 30) or control group (n = 30). The treatment gilts were fed a standard dry sow ration supplemented with COS at 0.12 and 0.24 g/gilt per d during gestation and lactation, respectively, and the control group was fed the standard dry sow ration only. The body weight, reproductive performance, milk production and litter size for each gilt and body weight of corresponding litters were recorded. The serum immunoglobulins (IgA, IgG, IgM) and secretory immunoglobulin A (sIgA) concentrations of gilts and piglets and fecal sIgA concertation of gilts were measured by Enzyme-linked immunosorbent assay (ELISA). Our study showed that maternal COS supplementation 1) significantly increased gilt body weight in late pregnancy (P < 0.05), 2) significantly increased milk production of gilts at different stages (d 1, 3, 7 and 19) of lactation (P < 0.05), 3) significantly increased body weight gain of piglets at weaning (P < 0.05), 4) significantly increased the serum concentrations of IgM and sIgA in piglets, and sIgA in fecal sample of gilts (P < 0.05), and 5) tended to increase the pregnancy success rate (P > 0.05) in the treatment group compared to the control group. These results suggest that maternal COS intervention in gilts can improve gilt milk production, piglet pre-weaning growth and immunity parameters in both gilts and piglets.

Abatement of enteric methane production from lactating Murrah buffaloes (Bubalus bubalis) with improving production performance and immune status through dietary supplementation of composite feed additive

Ruminant livestock production processes are the major sources of methane production in agriculture sector triggering global environmental pollution. Above 90% of world buffalo population present in Asian countries, India ranks first and contributes significantly to the environmental pollution by enteric methane emissions. In this study, we examined the effect of dietary composite feed additive supplementation on ruminal methane production, nutrient utilization, milk production and immune status of buffaloes (Bubalus bubalis). Eighteen lactating Murrah (Bubalus bubalis) buffaloes at early stage of lactation were divided into two groups of nine animals and fed a composite feed additive [consisted of (%, w/w) dried and ground leaves of Cordia dichotoma and Holoptelea integrifolia, 31.4 each; garlic oil, 0.6; sodium nitrate, 3.1; magnesium sulphate, 8.4; mustard oil, 12.6 and cottonseed oil, 12.5] which contained an ideal combinations of methane inhibitors, alternate hydrogen sinks and rumen stimulating agents to treatment (CFA) group animals along with basal feed of chaffed green sorghum (Sorghum bicolor) fodder, chaffed wheat straw and concentrate mixture for maintenance and milk production. The results showed a decrease (44.6%) in methane concentration in exhaled air of CFA group buffaloes with increase (p < 0.05) in digestibility of feed in comparison to control (CON). Total digestible nutrient (TDN) content of the ration fed to buffaloes of CFA group was significantly (p < 0.05) increased. The daily milk yield, 6% fat corrected milk (FCM) yield and immune response were also increased (p < 0.05) in CFA group. The study suggests that the supplementation of composite feed additive was effective to reduce enteric methane emissions and improvement in production performance and immune status of buffaloes.

Genome-wide association studies of lactation yields of milk, fat, protein and somatic cell score in New Zealand dairy goats

Background

Identifying associations between genetic markers and traits of economic importance will provide practical benefits for the dairy goat industry, enabling genomic prediction of the breeding value of individuals, and facilitating discovery of the underlying genes and mutations. Genome-wide association studies were implemented to detect genetic regions that are significantly associated with effects on lactation yields of milk (MY), fat (FY), protein (PY) and somatic cell score (SCS) in New Zealand dairy goats.

Methods

A total of 4,840 goats were genotyped with the Caprine 50 K SNP chip (Illumina Inc., San Diego, CA). After quality filtering, 3,732 animals and 41,989 SNPs were analysed assuming an additive linear model. Four GWAS models were performed, a single-SNP additive linear model and three multi-SNP BayesC models. For the single-SNP GWAS, SNPs were fitted individually as fixed covariates, while the BayesC models fit all SNPs simultaneously as random effects. A cluster of significant SNPs were used to define a haplotype block whose alleles were fitted as covariates in a Bayesian model. The corresponding diplotypes of the haplotype block were then fit as class variables in another Bayesian model.

Results

Across all four traits, a total of 43 genome-wide significant SNPs were detected from the SNP GWAS. At a genome-wide significance level, the single-SNP analysis identified a cluster of variants on chromosome 19 associated with MY, FY, PY, and another cluster on chromosome 29 associated with SCS. Significant SNPs mapped in introns of candidate genes (45%), in intergenic regions (36%), were 0-5 kb upstream or downstream of the closest gene (14%) or were synonymous substitutions (5%). The most significant genomic window was located on chromosome 19 explaining up to 9.6% of the phenotypic variation for MY, 8.1% for FY, 9.1% for PY and 1% for SCS.

Conclusions

The quantitative trait loci for yield traits on chromosome 19 confirms reported findings in other dairy goat populations. There is benefit to be gained from using these results for genomic selection to improve milk production in New Zealand dairy goats.

Limits to sustained energy intake. XXXI. Effect of graded levels of dietary fat on lactation performance in Swiss mice

The heat dissipation limit theory predicts that lactating female mice consuming diets with lower specific dynamic action (SDA) should have enhanced lactation performance. Dietary fat has lower SDA than other macronutrients. Here we tested the effects of graded dietary fat levels on lactating Swiss mice. We fed females five diets varying in fat content from 8.3 to 66.6%. Offspring of mothers fed diets of 41.7% fat and above were heavier and fatter at weaning compared with those of 8.3 and 25% fat diets. Mice on dietary fat contents of 41.7% and above had greater metabolizable energy intake at peak lactation (8.3%: 229.4±39.6; 25%: 278.8±25.8; 41.7%: 359.6±51.5; 58.3%: 353.7±43.6; 66.6%: 346±44.7 kJ day-1), lower daily energy expenditure (8.3%: 128.5±16; 25%: 131.6±8.4; 41.7%: 124.4±10.8; 58.3%: 115.1±10.5; 66.6%: 111.2±11.5 kJ day-1) and thus delivered more milk energy to their offspring (8.3%: 100.8±27.3; 25%: 147.2±25.1; 41.7%: 225.1±49.6; 58.3%: 238.6±40.1; 66.6%: 234.8±41.1 kJ day-1). Milk fat content (%) was unrelated to dietary fat content, indicating that females on higher fat diets (>41.7%) produced more rather than richer milk. Mothers consuming diets with 41.7% fat or above enhanced their lactation performance compared with those on 25% or less, probably by diverting dietary fat directly into the milk, thereby avoiding the costs of lipogenesis. At dietary fat contents above 41.7% they were either unable to transfer more dietary fat to the milk, or they chose not to do so, potentially because of a lack of benefit to the offspring that were increasingly fatter as maternal dietary fat increased.

Effect of abortion on milk production, health, and reproductive performance of Holstein dairy cattle

The objective of this study was to identify the effect of abortion on performance of Iranian Holstein cows that calved between 2005-2014. Abortion records were categorized in two groups: 1) new abortion (NLA), and 2) rebreeding abortion (RA). Production data (305-d milk, fat, and protein yields) were analyzed using PROC MIXED, number of inseminations per lactation period (INS), postpartum health disorders (PPHD), and culling records using PROC GLIMMIX, and calving to conception records using PROC PHREG of SAS software (SAS Institute, 2013). For each separate model, main herd-cow factors and all two-way significant interactions were considered in the analyses with results being reported for each calving status by lactation period. In total, 12.5 % of lactation periods were associated with at least one case of abortion, while 1.9 % of the lactation periods commenced with an abortion. Based on results from the present study, milk production decreased for cows having abortion classified as NLA or RA. Overall, when there was a RA, there was an increase in median days non-pregnant (DNP) by 132 d and INS by 1.6, whereas cows with NLA had median DNP of 15 d less and an INS of 0.17 less than cows with normal parturitions. Compared with cows with normal parturitions, cows with a NLA were 1.24, 1.88, and 2.41 times more likely to have PPHD, and be culled from the herd for involuntary reasons and reasons related to reproduction, respectively. The results of this study indicate abortions were associated with cow health and milk production and reproductive performance, indicating losses due to abortion are not only a direct result of the loss of a pregnancy.

Mutations in growth hormone gene affect stability of protein structure leading to reduced growth, reproduction, and milk production in crossbred cattle-an insight

The GH has a multifaceted role in growth, reproduction, and milk production. Nonsynonymous mutations identified as L153V were observed from GH1 (L) to GH2 (V) with higher genotypic frequency for GH1 being 0.87. GH2 (V) allele was identified as a rare allele and the population followed Hardy-Weinberg equilibrium. LL homozygote variant had significantly better growth, reproduction, and expected milk production at different ages in crossbred (CB) males. Reports are scanty explaining the molecular mechanism of how individuals with LV genotype were phenotypically inferior to that of wild-type LL. In the present study, it was explored that GH peptide with LV heterozygotes of GH gene, were observed to have reduced structural stability thermodynamically and thus functionally leads to reduced economic traits in CB animals. The fact was first time reported and confirmed through genomic analysis, bioinformatics, and later confirmed through immunohistochemistry. Differential expression analysis of the GH gene with respect to other genes in the hypothalamus-pituitary growth axis of CB cattle was also studied to have a complete insight of the GH gene.

The relationships among sire's predicted transmitting ability for daughter pregnancy rate and cow conception rate and daughter's reproductive performance in Canadian Holstein cows

The objectives of this study were to (1) characterize the variability for sire's predicted transmitting ability (PTA) for daughter's pregnancy rate (DPR) and cow conception rate (CCR), (2) determine the relationships among sire's PTA for DPR, sire's PTA for CCR, daughter's parity, and daughter's 305-d mature-equivalent (ME) milk production, and (3) evaluate the associations among sire's PTA for DPR and CCR and daughter's reproductive performance [pregnancy to first artificial insemination (P/AI), pregnancy by 150 d in milk (PR150) and pregnancy loss (PL) after first AI] in Canadian Holstein cows. The data were obtained from 822 lactating Holstein cows from 10 commercial dairy herds located in Alberta. Overall mean (range) for sire's PTA for DPR and CCR was -0.09 (-9.6 to 8.2) and -0.05 (-9.9 to 7.4), respectively. Sire's PTA for DPR was strongly and positively associated with sire's PTA for CCR (r = 0.89; P < 0.01). Sire's PTA for DPR and CCR were weakly and negatively associated with parity (r = -0.15 and -0.17, respectively; P < 0.01); however, the amount of phenotypic variation in sire's PTA for DPR and CCR explainable by parity was small (coefficient of determination; R² = 0.02). The daughter's 305-d ME milk production tended to be weakly but positively associated with sire's PTA for DPR (r = 0.06; P = 0.07) and CCR (r = 0.06; P = 0.10); however, the amount of phenotypic variation in daughter's 305-d ME milk production explainable by changes in sire's PTA for DPR or CCR was small (R² = 0.004 and 0.003, respectively). Overall P/AI, PR150 and PL were 38, 65 and 12%, respectively. Sire's PTA for DPR tended to be associated with P/AI (P = 0.08) but was significantly associated with PR150 (P = 0.03). For every unit increase in sire's PTA for DPR, the estimated probabilities for P/AI and PR150 increased by 6.2 and 7.5%, respectively. Sire's PTA for CCR was not associated with P/AI or PR150. Neither sire's PTA for DPR nor CCR were associated with PL. In summary, sire's PTA for DPR and CCR were highly variable and positively correlated. Sire's PTA for DPR was associated with daughter's P/AI and PR150, but sire's PTA for CCR was not associated with any of the measured reproductive outcomes. Therefore, selecting sires with high PTA for DPR has the potential to improve the reproductive efficiency of Canadian dairy herds.

Occurrence of on-farm risk factors and health effects of mycotoxins in dairy farms in Jordan

The aim of this study was to determine the occurrence of on-farm risk factors and health effects associated with contamination of dairy feeds with aflatoxins (AFs), zearalenone (ZEN), trichothecenes (T-2), deoxynivalenol (DON), and fumonisins (FB) in Jordan. A pre-tested and validated questionnaire was used to determine on-farm practices and health effects associated with high levels of mycotoxins. A total of 88 feed samples were collected from the 37 farms participating in the study and analyzed using commercially available ELISA kits. The mean total AF concentration exceeded the European Union (EU) limit in alfalfa (4%) and total mixed ration (TMR) (3%) samples. Similarly, levels exceeding EU limits were observed for T-2 in alfalfa (29%), TMR (30%), and corn silage (4%). The average concentrations of ZEN and FB were 300 ppb and 11,638 ppb, respectively, which were below the EU maximum limits in all feed samples examined. Intensive management system (OR = 7.70), imported feed (OR = 3.40), feed storage on the farm for more than 1-month duration (OR = 7.90), and not using antitoxins (OR = 2.30) were significantly (P < 0.05) associated with high levels of mycotoxins in feed samples. A significant correlation (P < 0.05) was evident between the presence of mycotoxins in dairy feed and feed refusal (R = 0.70), low milk production (R = 0.50), diarrhea problems (R = 0.60), infertility (R = 0.50), and repeated breeder problems (R = 0.80). Results show that mycotoxin contamination in dairy feeds is a problem in Jordan, and appropriate measures need to be undertaken to reduce risks to human and animal health and improve production.

Effects of periconceptional heat stress on primiparous and multiparous daughters of Holstein dairy cows

To meet growing worldwide demands for animal products, animal production will need to increase in capacity and efficiency. Every opportunity to improve animal protein yield should be considered and explored. Developmental programming is one such opportunity that has not yet been thoroughly investigated in farm animal production. While developmental programming can be advantageous for the survival of the offspring, it is often described in conjunction with negative consequences. The known and potential causes and mechanisms are numerous, often stemming from some sort of stress experienced during the prenatal or early postnatal period. One stressor that is particularly concerning for farm animal production is heat stress. Heat stress is known to elicit adaptations associated with developmental programming in several species, but has not been investigated in dairy cattle until recently. Multiple studies have shown that heat stress experienced during the periconceptional period is generally associated with reduced milk production of resulting offspring. This could be the result of adaptations within the pre-ovulatory oocyte or early developing embryo. Interestingly, in a few select comparisons, periconceptional heat stress was associated with greater milk production. This was only observed when dairy cattle calved in the spring, and would therefore be reaching peak milk production in late spring or early summer (in heat stress). This is consistent with the match/mismatch theory associated with developmental programming, where matched prenatal/postnatal environments confer advantageous adaptations and mismatched prenatal/postnatal environments are generally detrimental to the offspring. While these studies are important additions to our growing knowledge of heat stress impacts on dairy cow production, the broader implication of developmental programming requires further investigation.

Distinct expression patterns of aquaporin 3 and 5 in ductal and alveolar epithelial cells in mouse mammary glands before and after parturition

Milk osmolarity maintains an isotonic status for suckling infants during lactation. However, it remains unclear how the water content in milk is regulated in lactating mammary glands. In lactating mammary alveoli and ducts, mammary epithelial cells (MECs) are in direct contact with milk. In this study, we focus on two types of water channels, aquaporin 3 (AQP3) and AQP5, in alveolar and ductal MECs before and after parturition. AQP3 showed diffuse localization in the cytoplasm of ductal MECs but concentrated localization in the basolateral membrane of alveolar MECs during the late pregnancy and lactation periods. Translocation of AQP5 from the cytoplasm toward the apical membrane occurred in ductal MECs immediately before parturition. Subsequently, we examined the hormonal influences on the expression of AQP3 and AQP5 in cultured MECs in vitro. Progesterone and estrogen distinctly increased AQP3 and AQP5 in cultured MECs, respectively. Cotreatment with prolactin and dexamethasone significantly decreased both AQP3 and AQP5. Prolactin also facilitated the translocation of AQP5 into the apical membrane of MECs. In cultured MECs, AQP3 was homogeneously expressed in MECs, whereas AQP5 showed different expression levels between MECs regardless of the hormonal treatment. Different activation states of the prolactin/STAT5 pathway were also observed between ductal and alveolar MECs. These findings suggest that the expression pattern of AQP3 and AQP5 is distinctly regulated by lactogenic hormones in alveolar and ductal MECs before and after parturition. AQP5 expressed in ductal MECs may function as a water channel to regulate milk osmolarity in mice.

Milk production losses in Latxa dairy sheep associated with small ruminant lentivirus infection

Visna/Maedi is a disease of sheep caused by small ruminant lentivirus (SRLV) infection that is widespread throughout the world and that has been recognized to be present in the Basque Country (Spain) since the early 1980's. Nearly seven decades of studies have improved the knowledge on its clinical signs and epidemiology. However, its slow progressive nature, subclinical most of the time, makes difficult to assess its real impact on productive traits, a question of critical importance to balance out the economic costs it causes and the benefits of designing and deploying an eradication program. Development of a dairy breeding program since the 90 s in the local Latxa sheep population has provided data on milk productivity in several flocks where SRLV infection prevalence has been continuously monitored. This study analyses retrospectively the association between SRLV prevalence and production variables during ten yearly lactations in three Latxa dairy flocks with medium-high SRLV seroprevalence. Our results indicate that average standard lactation of seropositive sheep was 6.7 % lower than controls. The largest differences (p < 0.001) were observed at the ewe lifetime peak of production between second and fourth lactations. Lifelong milk and lamb production data indicated even a higher impact, with costs rising up to nearly 50 €/ewe/year. This substantial production decrease associated with subclinical SRLV infection in Latxa dairy sheep supports the benefit of establishing a SRLV control program. A rough cost-benefit analysis indicated that even in a medium-yielding breed, testing expenses would be largely covered by milk production improvement.

Effect of reducing energy intake during the dry period on milk production, udder health, and body condition score of Jersey crossbred cows in the tropical lower Gangetic region

To find out the effect of reducing energy intake during dry period on milk production, udder health, and body condition, the experiment was conducted on 14 Jersey crossbred cows during whole dry period and continued up to 120 days of lactation. Reduction in energy intake was done during far-off period for each dry cow of treatment group as compared to control group. Statistically analyzed data revealed that overall significantly (P < 0.01) lower DMI and WI were recorded in control than treatment group. Overall significantly (P < 0.01) higher total milk production was found in treatment than control group. Overall significantly (P < 0.01) lower milk SCC, MCMT, pH, and EC were found in treatment than control group. Nonsignificant difference in milk fat, SNF, total solid, total protein, and fat:protein ratio was found. Overall significantly (P < 0.01) better quality milk (MBRT) was found in treatment than control groups. BCS during dry period and at calving was significantly (P < 0.01) different between groups. Significantly (P < 0.01) higher plasma NEFA concentration was estimated in control than treatment groups in all stages. No significant difference was found for plasma concentrations of glucose, urea, and total protein. The coefficients of correlation indicated significant (P < 0.01) correlation among BCS, milk production, milk SCC, MCMT, pH, and EC. It can be concluded that reducing energy intake during far-off dry period can lead to achieve optimum BCS at calving. Suitable BCS at calving was beneficial to get higher milk production with improved quality, better maintenance of udder health and body condition of Jersey crossbred cows at tropical lower Gangetic region.

Fasciola hepatica seroprevalence in Northern German dairy herds and associations with milk production parameters and milk ketone bodies

Infections with the liver fluke Fasciola hepatica remain a serious problem in dairy herds causing significant production losses. In sheep, a strong relationship between F. hepatica infections and an increase in serum ketone bodies due to reduced feed intake and liver damage was demonstrated. We hypothesized that F. hepatica infections might contribute to an increase in milk ketone bodies in dairy herds. Thus, the objective of the study was to estimate the association between F. hepatica bulk tank milk (BTM) antibodies and milk production parameters (milk yield, milk protein, fat yield), somatic cell count (SCC) and the milk ketone bodies ß-hydroxybutyrate (BHB) and acetone, inferred from Fourier transform infrared (FTIR) spectrometry, via linear mixed model analysis. A further aim was to follow up the F. hepatica seroprevalence in dairy herds in the northern German region East Frisia. We collected BTM samples between October and December from 1022 herds in 2017 and 1318 herds in 2018. Overall, 33.1 % of the herds tested positive in 2017 and 37.0 % in 2018, showing decreased F. hepatica seroprevalences compared to prior seroprevalence studies in the same region in 2010, 2008 and 2006 (> 45 % positive herds). We estimated a significant negative association (P < 0.001) between herd F. hepatica infection category and average milk yield with a loss of -1.62 kg per cow per day in strongly infected herds compared to BTM ELISA negative herds. Moreover, F. hepatica infection category had a significant effect on herd average milk protein and fat yield (P < 0.001), showing a decrease of 0.06 kg for both parameters from BTM ELISA negative herds to strongly infected herds. No significant association with milk SCC was found (P = 0.664). Regarding ketone bodies, we estimated significant higher average BHB values in strongly infected herds compared to the other three infection categories in the model analysis (P = 0.002). The association between F. hepatica infection category and acetone values was not significant (P = 0.079). Besides primary ketosis, fasciolosis should be considered as differential diagnosis in dairy herds with increased BHB values.

Nicotine directly affects milk production in lactating mammary epithelial cells concurrently with inactivation of STAT5 and glucocorticoid receptor in vitro

Nicotine from tobacco smoke is absorbed into the bloodstream and transferred into breast milk in breastfeeding mothers. Smoking causes a decrease in breast milk volume, adverse changes to the milk composition, and a shortened lactation period. Breast milk is produced by mammary epithelial cells (MECs) in mammary glands during lactation. However, it remains unclear whether nicotine directly affects milk production in lactating MECs. To address this issue, we prepared a culture model with high milk production ability and less-permeable tight junctions (TJs) by seeding mouse MECs on a cell culture insert. Lactating MECs showed expression of α2, α3, β2, and β4 of nicotinic acetylcholine receptors. The high concentration of nicotine at 10-100 μM inhibited β-casein secretion and caused abnormal localization of TJ proteins. We subsequently investigated whether nicotine at a physiological concentration could affect lactating MECs. Nicotine at 1.0 μM directly inhibited α- and β-casein secretion in lactating MECs concurrently with inactivation of STAT5 and glucocorticoid receptor without affecting the TJ barrier. Nicotine treatment also induced MEC apoptosis concurrently with inactivation of Akt. These results support the adverse effects of nicotine on breastfeeding in smoking mothers.

Characterization of small-scale dairy farms and its relation to water use efficiency in the Mexicali Valley, Mexico

A survey was completed to determine water use by small-scale dairy farms in Mexicali Valley of Mexico and to associate it with dairy production parameters. Mexicali Valley surrounds the capital city of the state Baja California, Mexicali. Sixty-one smallholders were interviewed in person in this rural area of northwestern Mexico. On average, small dairy holders had more than 20 years of experience and were ~ 55 years of age; people working on their farms are especially relatives. A low percentage was literate (20%), and they belong to a local dairy association. Milk yield/cow/year does not reach 4000 kg of milk and 75% of producers do not follow a defined management program for their cattle. Hand-milking is still practiced by 27% of the producers, and there is a general lack of infrastructure to maintain milk in a refrigerated state so that there is a very high risk of zoonotic diseases. Water use efficiency (WUE) was linearly correlated (P < 0.05) with total irrigated area, but not with animal production parameters. Regression equations constructed to explain WUE exhibited low adjustment, and WUE was not associated (P > 0.05) with milk yield. Small dairy producers in Mexicali Valley are in a generally poor situation with low water use practices; however, required more government support to increase their benefits from this livestock activity.

A comparison of milk production from Holstein Friesian and Jersey cattle breeds under hot climate of Oman

Data of milk production and performance under Oman climatic conditions are limited. The current study presents a 9-year analysis of daily milk performance of Holstein and Jersey cattle breeds born and raised in Oman and fed similar diets of concentrate and Rhodes grass hay. Data on the daily cow's milk production, during the entire lactation period for nine consecutive milking years between 2009 and 2018, were collected. The data was introduced to a linear mixed model and was analyzed to evaluate the breed variations in milk production across lactations and across years. Holstein Friesian (HF) cows had significantly (P < 0.001) higher daily milk production of 17.6 ± 0.4 kg/cow/day compared to 11.7 ± 0.8 kg/cow/day for Jersey cows. Across years, we observed a gradual annual improvement in total milk production in both HF and Jersey breeds of 5% and 6%, respectively. The highest daily milk production was in the third and fourth lactations for HF cows and in the second and third lactations for Jersey cows. In a region where much of the expected demand in milk will be met by exotic breeds and importation, our results provide an insight into the performance of temperate breeds in hot and arid climatic conditions. As such, our results shall be useful for dairy producers seeking to maximize milk production under such conditions.

Identification of single nucleotide polymorphisms of PIK3R1 and DUSP1 genes and their genetic associations with milk production traits in dairy cows

Background

Previously, phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1) and dual specificity phosphatase 1 (DUSP1) were identified as promising candidate genes for milk production traits due to their being differentially expressed between the dry period and the peak of lactation in livers of dairy cows. Hence, in this study, the single nucleotide polymorphisms (SNPs) of PIK3R1 and DUSP1 genes were identified and their genetic associations with milk yield, fat yield, fat percentage, protein yield, and protein percentage, were investigated using 1067 Chinese Holstein cows from 40 sire families.

Results

By re-sequencing the entire coding region and 2000 bp of the 5′ and 3′ flanking regions of the two genes, one SNP in the 5′ untranslated region (UTR), three in the 3′ UTR, and two in the 3′ flanking region of PIK3R1 were identified, and one in the 5′ flanking region, one in the 3′ UTR, and two in the 3′ flanking region of DUSP1 were found. Subsequent single-locus association analyses showed that five SNPs in PIK3R1, rs42590258, rs210389799, rs208819656, rs41255622, rs133655926, and rs211408208, and four SNPs in DUSP1, rs207593520, rs208460068, rs209154772, and rs210000760, were significantly associated with milk, fat and protein yields in the first or second lactation (P values ≤ 0.0001 and 0.0461). In addition, by the Haploview 4.2 software, the six and four SNPs in PIK3R1 and DUSP1 respectively formed one haplotype block, and the haplotype-based association analyses showed significant associations between their haplotype combinations and the milk traits in both two lactations (P values ≤ 0.0001 and 0.0364). One SNP, rs207593520(T/G), was predicted to alter the transcription factor binding sites (TFBSs) in the 5′ flanking region of DUSP1. Further, the dual-luciferase assay showed that the transcription activity of allele T in rs207593520 was significantly higher than that of allele G, suggesting the activation of transcriptional activity of DUSP1 gene by allele T of rs207593520. Thus, the rs207593520 SNP was highlighted as a potential causal mutation that should be further verified.

Conclusions

We demonstrated novel and significant genetic effects of the PIK3R1 and DUSP1 genes on milk production traits in dairy cows, and our findings provide information for use in dairy cattle breeding.

Relationships between failure of passive transfer and subsequent mortality, bodyweights and lactation performance in 12-36 month old heifers on pasture-based, seasonal calving dairy farms in New Zealand

This study examined the long-term effects of failure of passive transfer of immunity (FPT; diagnosed at 1-8 days of age) on subsequent milk production, growth, reproduction, and lactation performance in dairy heifers from 12 to 36 months of age. A total of 34 farms from the Waikato and Canterbury regions of New Zealand were enrolled in 2015. Each farm was visited on three occasions during the seasonal calving period (early, middle, and late). Blood samples were collected at each visit from 20 replacement heifer calves aged between 1 and 7 days to test for FPT. These heifers (n=1879) were monitored from birth until the end of their first lactation. From 12 months of age onwards, animals were weighed at 15 and 22 months, pregnancy tested 100 days following their first mating, and milk was sampled between 3-4 times during their first lactation to determine milk volume and milk component yields. Farmers recorded any mortality events. FPT had no effect on the odds of mortality from 12 to 22 months (P=0.57) and 12 to 34 months of age (P=0.44). There was no difference in bodyweight at 15 months (P=0.17) and 22 months of age (P=0.95), no significant difference in the odds of being diagnosed pregnant (OR 1.44; 95% CI 0.82-2.69), and no effect on milk solids (fat plus protein) yields (P=0.67). No associations were observed between serum total protein (STP) concentration and milk solids yields (P=0.22) and any other milk parameters. The data from this study indicate that FPT did not adversely affect productivity, performance, or mortality beyond 12 months of age in heifers reared in pasture-based systems.