Increased Milk Yield Research Articles

Influence of lactation number and parity on milk yield of Saanen goat’s breed

ABSTRACT The aim of this research was to determine the influence of lactation number and parity on milk yield of Saanen goat’s breed. It has been concluded that milk yield was higher for goats that had given birth to twins and three kids than for goats that had given birth to a single kid (P<0.05). The longevity has a great positive impact on production, given that goats in the fifth lactation produced more milk than goats in first or second lactation (P<0.05), while goats in the sixth lactation still produced more milk than goats in first lactation (P<0.05). During the period from 2014- 2019, the research was conducted on a farm of multiparous Saanen goats in Vojvodina (northern part of Serbia). In the observed period, the farm had between 350 and 400 goats per milking, and the research included a total of 1,628 concluded lactations, within which the first lactations were the most 484, then the second 381. According to the number of lactations, goats were grouped into classes from one to seven and from one to three for parity. By comparing each individual lactation, it was determined that in first lactation goats produced significantly lower milk than goats in the rest lactations(P<0.05), except the seventh. Research has shown that lactation number has a significant influence on milk yield (P=0.00). Increasing the fertility of goats significantly affects the production capacity of dairy goats, since does with a larger number of kids in the litter had a significantly higher milk production (P<0.05). Due to the larger number of kids in the litter, milk production also increases. Likewise, it is assumed that the increase in milk yield of goats with two and three kids is a consequence of a larger placenta, i.e. stronger lactogenic activity during pregnancy.

Effects Of Aqueous Extract Of Momordica Balsamina L. On Milk Yield, Lactogenic Hormones And Biomarkers Of Oxidative Stress In Lactating Wistar Rats

Background: Momordica balsamina L. is a medicinal plant used in traditional medicine to stimulate milk production. The study was designed to evaluate the effect of aqueous extract of Momordica balsamina L. on milk yield, serum lactogenic hormones and biomarkers of oxidative stress in lactating. Material and methods: Twenty five female lactating Wistar rats (n = 25) with 4 pups each were divided into five (5) groups of five (5) rats each and treated as follows: Group I: 1ml/kg distilled water; group II: 5 mg/kg metoclopramide; group III: 200 mg/kg; group IV: 400 mg/kg and group V: 800 mg/kg of Momordica balsamina L., respectively. Administration was done orally once daily at 18:00 hr for a period of 10 days, during which the milk yield was calculated daily at 18 hr after gavage. At the end of the experiment, the Wistar rats were sacrificed and blood samples and mammary tissue were harvested for analysis of prolactin, growth hormone and biomarkers of oxidative stress and histological studies. Results: There was a significantly lower serum prolactin level (p< 0.05) in the 800 mg/kg treated group when compared to the control. Serum growth hormone level was significantly higher in all the treated as compared with the control group (p< 0.05). Momordica balsamina L. stimulated a significant increase (p< 0.05) in milk yield at 400 mg/kg when compared to the control group. It also caused a significantly lower (p < 0.05) serum activity of superoxide dismutase in the 400 mg/kg and 800 mg/kg groups compared to the control group. While, serum glutathione peroxidase and catalase were significantly lower (p< 0.05) in the 800 mg/kg treated groups, when compared to the control group. Significantly higher (p< 0.05) serum Melondialdehyde levels were observed in the treated compared to the control. The mammary glands of rats treated with the extract showed lobuloalveolar development at 400 mg/kg. Conclusion: The study highlighted that Momordica balsamina L. stimulates mean milk yield, increase serum growth hormone and enhance lobuloaveolar development.

Genetic parameters and genetic trends of conformation and management traits in Dairy Gir cattle

ABSTRACT The objective of this study was to estimate genetic parameters and genetic trends of different conformation and management traits regularly measured within the context of the National Dairy Gir Breeding Program (PNMGL). The estimation of genetic and residual variances for each trait was performed using average information restricted maximum likelihood (AI-REML) procedure in AIREMLF90 program software. The population was divided into three subpopulations constituted by measured females (with phenotype records), all females, and males. Linear regressions were applied for each trait, considering two periods of birth (1st period: 1938-1996; 2nd period: 1997-2012). The estimated heritability of conformation and management traits varied from 0.01 to 0.53, denoting a perspective of genetic improvement through selection and corrective matings for purebred Dairy Gir populations. The average genetic changes in conformation and management traits were, in general, variable and inexpressive, showing that the selection of Dairy Gir may have had been directed essentially to increase milk yield. The analysis of the two periods of birth indicated that some linear traits present progress (although inexpressive) in the 2nd period (more recent period).

Effects of pomegranate peel and olive pomace supplementation on reproduction and oxidative status of rabbit doe.

The current study aimed to investigate the effects of pomegranate peel and olive pomace supplementation on the reproductive hormones, antioxidative status, reproductive capacity and maternal behaviour of rabbit does. Forty does were used for the experiments. The animals were randomly assigned to four groups of ten does. One group was fed on the control diet and was considered the control group (C). The second group was supplemented with 4.5% pomegranate peel in their diet (P), the third group was supplemented with 10% olive pomace in their diet (O), and the fourth group was supplemented with a mixture of pomegranate peel and olive pomace (PO). Compared with the control does, group P showed significantly increased serum levels of gonadotropic hormones and oestradiol-17β two hours after mating, on the 20th day of lactation and after weaning; significantly increased progesterone levels at mid-pregnancy; and significantly increased in prolactin levels on the 10th day of lactation. Additionally, the results revealed significant increases in total DNA, protein concentration, litter size, milk yield and nest traits of groups P and PO. In conclusion, pomegranate peel supplementation improves the reproductive performance of does and increases their antioxidant parameters.

Meta-analysis-based estimates of efficiency of calcium utilisation by ruminants

The most abundant mineral in the body of animals is Ca, which has crucial importance for the regulation of various processes. The maintenance of Ca balance has become more challenging, especially in lactating ruminants, owing to the increased milk yields and thus Ca requirement. To determine the Ca requirement, factors such as Ca secretion via milk or Ca deposition in body tissues and conception products are summed up to the net Ca requirement. Nevertheless, dietary Ca cannot be completely utilised by the animal to cover the net Ca requirement, therefore a value for the efficiency of Ca utilisation is applied, which is the maximum proportion of Ca from the feed that the animal can use for covering the net requirement. However, current estimates for the efficiency of Ca utilisation are inconsistent. Therefore, the objective of the present meta-analysis was to estimate the efficiency of Ca utilisation for ruminants, considering the Ca supply of the animal. A data set of 223 observations was compiled from 37 studies, including data on cattle and small ruminants. Standardised Ca digestibility was calculated from data on Ca intake and faecal Ca excretion, corrected for faecal endogenous losses. Furthermore, a data subset on only lactating ruminants was created. For this subset, Ca excretion via faeces and urine and standardised Ca digestibility were related to the Ca supply of the animal. An exponential function was fitted to standardised digestibility data in response to Ca concentration in the diet and Ca supply, revealing that standardised Ca digestibility decreased with increasing dietary Ca concentration and Ca supply. The median for standardised Ca digestibility was 40%, with a remarkable variation between 9% and 88%. In response to Ca supply, faecal Ca excretion increased in a strong linear manner (slope = 0.76, R2 = 0.96). Excretion of Ca via urine was very low even when Ca supply was very high. To conclude, Ca digestibility is a suitable indicator for the efficiency of Ca utilisation, since excessive Ca is almost completely excreted in faeces; however, Ca digestibility has to be determined at a Ca supply level below the requirement of the animal. To date, only very limited number of data have been reported for such supply conditions. Comparative studies using various Ca sources are suggested for future studies but should be conducted using a marginal Ca supply level.

Effects of achromatic and chromatic lights on pupillary response, endocrinology, activity, and milk production in dairy cows.

Artificial light can be used as a management tool to increase milk yield in dairy production. However, little is known about how cows respond to the spectral composition of light. The aim of this study was to investigate how dairy cows respond to artificial achromatic and chromatic lights. A tie-stall barn equipped with light-emitting diode (LED) light fixtures was used to create the controlled experimental light environments. Two experiments were conducted, both using dairy cows of Swedish Red and light mixtures with red, blue or white light. In experiment I, the response to light of increasing intensity on pupil size was evaluated in five pregnant non-lactating cows. In experiment II 16h of achromatic and chromatic daylight in combination with dim, achromatic night light, was tested on pregnant lactating cows during five weeks to observe long term effects on milk production, activity and circadian rhythms. Particular focus was given to possible carry over effects of blue light during the day on activity at night since this has been demonstrated in humans. Increasing intensity of white and blue light affected pupil size (P<0.001), but there was no effect on pupil size with increased intensity of red light. Milk yield was maintained throughout experiment II, and plasma melatonin was higher during dim night light than in daylight for all treatments (P<0.001). In conclusion, our results show that LED fixtures emitting red light driving the ipRGCs indirectly via ML-cones, blue light stimulating both S-cones and ipRGCs directly and a mixture of wavelengths (white light) exert similar effects on milk yield and activity in tied-up dairy cows. This suggests that the spectral composition of LED lighting in a barn is secondary to duration and intensity.

Design of Free Stalls for Dairy Herds: A Review

Lying is an important behavior of dairy cattle. Cows should spend more than 50% of a day lying as it has a high impact on their milk yield and animal welfare. The design, size, and flooring properties of the free stalls influence the time cows spend lying, the way they lie down, and their rising movements. The purpose of this review is to provide an overview of the currently available information with the aim to assist farmers and advisors to come to an optimal design of the free stalls. The design of the free stalls should enable the cows to move and lie in positions as natural as possible. Cows should rest, with all parts of the body, on a clean, dry and soft bed, be able to stretch their front legs forward, lie on their sides with unobstructed space for their neck and head, and rest with their heads against their flanks without hindrance from a partition. When they stand, they should not be hindered by neck rails, partitions, or supports. A comfortable place for cows to lie down helps cows to stay healthy, improve welfare, and increase milk yield. Hence, the probability of a longer productive life for the cows increases and the number of replacements per year decreases.

A 12 kb multi-allelic copy number variation encompassing a GC gene enhancer is associated with mastitis resistance in dairy cattle.

Clinical mastitis (CM) is an inflammatory disease occurring in the mammary glands of lactating cows. CM is under genetic control, and a prominent CM resistance QTL located on chromosome 6 was reported in various dairy cattle breeds. Nevertheless, the biological mechanism underpinning this QTL has been lacking. Herein, we mapped, fine-mapped, and discovered the putative causal variant underlying this CM resistance QTL in the Dutch dairy cattle population. We identified a ~12 kb multi-allelic copy number variant (CNV), that is in perfect linkage disequilibrium with a lead SNP, as a promising candidate variant. By implementing a fine-mapping and through expression QTL mapping, we showed that the group-specific component gene (GC), a gene encoding a vitamin D binding protein, is an excellent candidate causal gene for the QTL. The multiplicated alleles are associated with increased GC expression and low CM resistance. Ample evidence from functional genomics data supports the presence of an enhancer within this CNV, which would exert cis-regulatory effect on GC. We observed that strong positive selection swept the region near the CNV, and haplotypes associated with the multiplicated allele were strongly selected for. Moreover, the multiplicated allele showed pleiotropic effects for increased milk yield and reduced fertility, hinting that a shared underlying biology for these effects may revolve around the vitamin D pathway. These findings together suggest a putative causal variant of a CM resistance QTL, where a cis-regulatory element located within a CNV can alter gene expression and affect multiple economically important traits.

The level of milk productivity and reproductive ability of cows depending on the duration of the open days period

The open days period is one of the components of the physiological cycle of the cow, during which it must be prepared for effective insemination. The duration of this period as a production indicator gives a general idea of the reproductive traits of the herd as a whole, and of each animal in particular. In order to increase milk production, it is possible to extend the open days period to obtain a longer lactation. Studies of this issue show that at the same time the dry period also extends and the average daily milk yield as the whole for lactation decreases. The purpose of the research was to determine the level of milk productivity and reproductive ability of cows depending on the duration of the open days period. The research has been carried out under the conditions in the APC “Emurtlinsky” in the Tyumen region, which is a breeding farm for the breeding of cattle of Holstein breed. It has been found that with an increase in the duration of the open days period from 93 days in the control group to 146 days in the experimental group the duration of barrenness was 3 and 56 days, respectively. It has been found that on the 1st day of milk yield per cow, the milk loss was 4,9 kg, and the absolute annual milk loss in the cows of the experimental group was in the range of 275 kg. The conducted studies suggest that with the increase in the duration of calving interval, there is the decrease in the milk yield of cows per year. The use of cows with the increase in the open days period above the norm recommended by specialists is unjustified. The increase in milk yield due to the lengthening of the lactation period is not effective, because it eventually leads to the increase in the number of days of barrenness and milk loss.

Effects of feeding urea-treated triticale and oat grain mixtures on ruminal fermentation, microbial population, and milk production performance of midlactation dairy cows

Abstract The starch content of triticale and oat grains provides much of their readily available energy. Synchronizing energy and nitrogen in the rumen is important in optimizing profitability; for this reason, ammonia processing of these grains was evaluated for its potential to modify ruminal fermentation and to improve milk production performance. A mixture of ground triticale and oats (CONG, at a ratio of 60:40 on a dry matter basis) was treated with urea (5 kg/1000 kg) and urease additive (20 kg/1000 kg) containing 200 g/kg of moisture, for 2 wk (UREG). The urea treatment enhanced the pH and CP content of grains by 34% and 52%, respectively. In a batch culture study, CONG or UREG as the only substrate was incubated in a buffered ruminal fluid. Compared to CONG, UREG increased pH, total VFA concentration, total gas, and disappearance of DM, while reducing CH4 production, whereas NH3 concentration increased and entodiniomorph counts tended to increase. In the in vivo study, cows were randomly allocated to two dietary groups (n = 24) and were offered TMR based on maize and grass silage, containing either 155 g/kg of CONG and 80 g/ kg of soybean meal (CONT) or 155 g/kg of UREG and 59 g/kg of soybean meal (URET) for 31 d. Ruminal fluid was collected (n = 10) using rumenocentesis. The relative abundances of Streptococcus bovis decreased, but Megasphaera elsdenii, methanogens, and ammonia-producing bacteria increased by URET. Entodiniomorph and holotrich counts were decreased by URET. Feeding with URET increased ruminal pH and concentrations of total VFA, acetate, branched-chain VFA, and NH3. Feeding with URET also increased milk yield. These results demonstrate that replacing untreated triticale and oat grains with urea-treated grains can beneficially modulate ruminal microbiota and fermentation, consequently improving production performance and profitability.

Effect of bypass fatty acid and Tinospora cordifolia supplementation on production performance and milk fatty acid profiling in Murrah buffaloes (Bubalus bubalis).

Buffaloes contribute about 49% of total milk production and are considered as major milk-producing animals in India. During the early stage of lactation, mostly high producing animals suffer from negative energy balance (NEB) due to imbalance between the needs and availability of energy, and this NEB has a negative impact on production and health of buffaloes. Taking this into consideration, a study was conducted at National Dairy Research Institute, Karnal on 20 freshly calved healthy Murrah buffaloes (Bubalus bubalis). Buffaloes were grouped depending on their previous milk yield, body weight, and parity as T0 (control), T1 (fatty acids), T2 (Tinospora), and T3 (mix) groups having five animals each. Supplementation of 150g of bypass fatty acids in T1 group, 150g of Tinospora powder in T2 group, and combination of 150 of bypass fatty acid and 150g of Tinospora powder in T3 group over and above the standard feeding schedule was done for a duration of 90days whereas standard feeding schedule was followed in T0 group. A significant (P < 0.05) increase in average daily milk yield was observed in T1 (10.06 ± 0.56kg/d/h), T2 (10.30 ± 0.53kg/d/h), and T3 (10.11 ± 0.48kg/d/h) in comparison to control group (8.05 ± 0.38kg/d/h). Significantly (P < 0.05) higher milk fat percent and total solids were also recorded in treatment groups over the control group. Other milk constituents (SNF, protein, lactose, ash) and milk properties (pH, conductivity, freezing point, density) remained unaffected by the supplementations. The somatic cell count values were significantly (P < 0.05) decreased in T2 and T3 with the advancement in the lactation in comparison to T0 and T1. Supplementation also leads to significantly (P < 0.05) higher MUFA and PUFA contents in milk of treatment group buffaloes in comparison to control group. The study outcomes state that combination of bypass fatty acids and Tinospora cordifolia supplementation improves milk production and its composition in lactating Murrah buffaloes.

Feeding diets varying in starch concentration supplemented with palmitic acid or stearic acid: Effects on performance, milk fatty acid profile, and metabolic parameters of postpartum dairy cows

The objective of this study was to investigate the effects of dietary fat supplement rich in palmitic acid or stearic acid on milk yield and composition, fatty acid profile, energy partitioning, and metabolic parameters of dairy cows fed low or high starch diets from d 1 to 28 of the postpartum period. Forty-four multiparous Holstein cows were used in a complete randomized block (based on parity, and previous 305-d milk yield); 2 × 2 arrangement with two dietary starch levels [high starch (HS); 260 g/kg of diet dry matter (DM) versus low starch (LS); 210 g/kg of diet DM] with either palmitic acid (PA) or stearic acid (SA) supplementation at the level of 15 g/kg of diet DM. A basal close-up diet (6.19 MJ/kg of diet DM, NEL; 200 g/kg starch) was fed to animals prior to calving. Regardless of the fatty acid (FA) type, cows fed HS diets had a higher dry matter and NEL intake, milk protein and lactose content, and a more positive energy balance than cows fed LS diets during the postpartum period. Compared with HS diets, LS diets reduced energy toward body reserves and maintenance as a fraction of the NEL intake. Although there was no main effect of PA or SA supplement on intake and energy balance, the effect of fat supplementation depended on dietary starch levels for milk yields and milk energy as a fraction of the NEL intake. Stearic acid increased milk yield in HS diets while PA tended to increase yield in LS diets. Supplementation of PA partitioned less energy toward milk (and more energy for maintenance) in HS diets than LS diets. Moreover, the C16:0 FA concentration in milk fat was higher, and the polyunsaturated FA (PUFA) and C18:1 cis-9 FA were lower in PA supplemented cows fed HS diets but not cows fed LS diets. High starch rations increased de novo FA concentrations in milk and decreased C18:0 and preformed FA concentrations compared with LS diets. Also, HS diets tended to have higher levels of insulin and lower levels of beta-hydroxybutyrate (BHBA) than LS diets. In conclusion, the HS diet was more beneficial to improving the energy balance (EB) of dairy cows than LS diets during the early postpartum period. Also, interactions between dietary starch levels and FA supplement for the variables measured in the current study (e.g. milk yield or FA profile) indicate that the response to fat supplements rich in specific FA differed on the basis of dietary starch concentrations.

РЕЗУЛЬТАТИВНОСТЬ РАЗНЫХ МЕТОДОВ ОЦЕНКИ БЫКОВ-ПРОИЗВОДИТЕЛЕЙ ЧЕРНО-ПЕСТРОЙ ПОРОДЫ ПО КАЧЕСТВУ ПОТОМСТВА

The paper presents results of assessing black-and-white bulls by the quality of the offspring with application of different methods. The evaluation of bulls was carried out with application of the “daughter-mother” method in the conditions of Volzhsky Research Institute of Hydraulic Engineering and Land Reclamation. The valuation showed that the bulls Aist 7 and Muscat 8 increased milk yield of daughters, in comparison with mothers, by 951 and 486 kg, or by 26.7 and 12.9%. The rest of the servicing bulls reduced milk yield of the offspring by 46 - 1019 kg (1.1 - 24.7%). When assessing the bulls using the “daughterpeer” method, the highest milk productivity was shown by the descendants of Sazan 25 and Aist 7 of Vis Back Ideal line, which surpassed their peers in milk yield by 273 and 419 kg, or by 3.8 and 5.7%, respectively. The producers Snop 57 (his 17 daughters had average milk yield of 4224 kg for the first lactation with milk fat of 3.80%) and Muscat 8 (with an average milk yield of daughters of 4254 kg , milk fat - 3.83%) are also of significant value for the breeding work of this farm. According to the assessment results, the producer Aist 7 was assigned to the breeding category of A1 of milk yield improvers. Bulls Sazan 25 and Muscat 8 are also rated as daughters’ milk yield improvers and are categorized as A2 and A3. All bulls evaluated by comparing daughters to the breed standards are improvers of daughters’ milk yield (+ 454-1860 kg).

ВЛИЯНИЕ ВОСПРОИЗВОДИТЕЛЬНЫХ КАЧЕСТВ НА МОЛОЧНУЮ ПРОДУКТИВНОСТЬ КОРОВ СИММЕНТАЛЬСКОЙ ПОРОДЫ

The applicability of the work is to identify the possibility of productivity increase of cows of the Simmental breed due to reproductive qualities. The aim of the work is to assess the influence of the first insemination age, service period and dry period on milk productivity of Simmental cows. The research is aimed at studying milk productivity of Simmental cows with different levels of reproductive qualities. The obtained data were statistically processed in Excel. Descriptive statistics methods were used. The object of the research were Simmental cows of “ Tasaliev D.M. “ farm of Kaliningrad region. As a result of the study, a relation was established between the age of the first successful insemination, the service period duration, the dry period duration and parameters of milk productivity. The age of the first successful insemination at 18-24 months has the most beneficial effect on subsequent milk productivity. A service period of 90-120 days has a positive effect on milk yield increase for 305 days of lactation, a longer service period negatively affects the mass fraction of milk fat. Prolonged service period results in a calf loss of 100 calves per year. With an increase of dry period duration, the mass fraction of milk fat increases, but milk yield decreases. The influence of reproductive qualities on mass fraction of milk protein is insignificant. According to the results of the studies, it can be considered that reproductive qualities, in combination with other factors, influence milk productivity of Simmental cows.

Performance perception of Canadian dairy producers when transitioning to an automatic milking system

Adoption of automated milking systems (AMS) has increased exponentially around the world in recent years. The objective of this observational study was to evaluate how producer perception of changes in cow-average milk yield and somatic cell count (SCC) compared with the actual changes in their herds after the introduction of AMS in Canadian commercial dairy herds. Data were collected (in 2014 and 2015) through a survey of 97 Canadian dairy herds that shifted to AMS from 2000 to 2014. Producers were asked their perception about milk yield and SCC changes (increase, decrease, or no change) after AMS introduction. Actual herd performance data were obtained from dairy herd improvement organizations. Differences between the 12-mo rolling herd-average milk yield (kg/cow per year) and SCC (cells/mL) at the closest test 2 yr after transitioning to AMS and at the last test before the transition were calculated and compared with the producer perception answers. After AMS adoption, milking herd size, milk yield, SCC, and number of AMS units per herd averaged (± standard deviation) 99.8 ± 54.4 cows, 9,619 ± 1,354 kg/cow per year, 248,825 ± 97,286 cells/mL, and 1.9 ± 1.1 units, respectively. On average, after AMS introduction, herd size, milk yield, and culling rate increased by 11.3 cows, 441 kg/cow per year, and 1.3%, respectively, and calving interval decreased by 7 d. For producers who perceived an increase, actual milk yield and SCC increases averaged (mean ± standard deviation) +534 ± 1,003 kg/cow per year and +56,679 ± 66,662 cells/mL, respectively. Alternatively, for producers who perceived a decrease, actual milk yield and SCC decreases averaged −984 ± 658 kg/cow per year and −26,976 ± 94,099 cells/mL, respectively. An actual milk yield change of +83.1 ± 1,113.3 kg/cow per year and an SCC change of +6,135 ± 72,609 cells/mL were observed in the herds in which the dairy producers perceived no change with the AMS introduction. Hence, dairy producers were, on average, able to discern their actual milk yield and SCC changes after AMS adoption. However, the proportions of dairy producers who accurately perceived their actual milk yield and SCC changes after AMS introduction were 39.4% for milk yield (increase: 36.3%; decrease: 100.0%; and no change: 45.5%) and 46.7% for SCC (increase: 50.0%; decrease: 39.0%; and no change: 54.1%). From these results, we concluded that several dairy producers distorted their actual milk yield and SCC changes or were not fully aware of those changes.

Glutamine Regulates Cell Growth and Casein Synthesis through the CYTHs/ARFGAP1-Arf1-mTORC1 Pathway in Bovine Mammary Epithelial Cells.

In the dairy industry, glutamine (Gln) is often used as a feed additive to increase milk yield and quality; however, the molecular regulation underneath needs further clarification. Here, with bovine mammary epithelial cells (BMECs), the effects and mechanisms of Gln on cell growth and casein synthesis were assessed. When Gln was added or depleted from BMECs, both cell growth and β-casein (CSN2) expression were increased or decreased, respectively. Overexpressing or inhibiting the mechanistic target of rapamycin (mTOR) revealed that Gln regulated cell growth and CSN2 synthesis through the mTORC1 pathway. A similar intervention of ADP-ribosylation factor 1 (Arf1) uncovered that Gln activated the mTORC1 pathway through Arf1. We next observed that both guanine nucleotide exchange factors, Cytohesin-1/2/3 (CYTH1/2/3, CYTHs) and ADP-ribosylation factor GTPase activating protein 1 (ARFGAP1), interacted with Arf1. Inhibiting CYTHs or ARFGAP1 showed that Gln supplement or depletion activated or inactivated Arf1 through CYTHs or ARFGAP1, respectively. Collectively, this study demonstrated that Gln positively regulated cell growth and casein synthesis in BMECs, which works through the CYTHs/ARFGAP1-Arf1-mTORC1 pathway. These results greatly enhanced current understanding regarding the regulation of the mTOR pathway and provided new insights for the processes of cell growth and casein synthesis by amino acids, particularly Gln.

Dietary Arginine Supplementation during Gestation and Lactation Increases Milk Yield and Mammary Lipogenesis in Rats.

Arginine, an essential amino acid during the reproductive period, has been shown to enhance lactation performances in livestock. Whether it could help mothers with breastfeeding difficulties is not known. This study aimed to determine whether dietary arginine supplementation would enhance milk production in rat dams nursing large 12-pup litters and, if so, what mechanisms are involved. In 3 series of experiments, differing in dam killing timing, 59 primiparous, pregnant Sprague-Dawley rats (mean±SD weight: 254±24.7g) were randomly assigned to receive either 1) an AIN-93G diet supplemented with l-arginine at 2.0% (ARG diet), through lactation and gestation (AGL group); 2) a control AIN-93G diet including at 3.5% an isonitrogenous mix of amino acids that are not essential for lactation (MA diet), during gestation and lactation (MA group); or 3) the MA diet during gestation and the ARG diet during lactation (AL group). Milk flow was measured using deuterated water enrichment between days 11 and 18. Plasma hormones and mammary expression of genes involved in lactation were measured using ELISA and qRT-PCR, respectively, at lactation days 12, 18, or 21 in the 3 experiments. Data were analyzed by ANOVA. Dam food intake, pup weight gain, milk flow normalized to dam weight, and milk fat concentration were 17%, 9%, 20%, and 20% greater in the AGL group than in the MA group, respectively (P<0.05). Genes involved in lipogenesis and lipid regulation were overexpressed ≤2.76-fold in the mammary gland of AGL dams compared with MA dams (P<0.05) and plasma leptin concentration was 39% higher (P=0.008). Milk flow and composition and mammary gene expression of the AL group did not differ from those of the MA group, whereas milk fat concentration and flow were 26% and 37% lower than in the AGL group, respectively. Arginine supplementation during gestation and lactation enhances milk flow and mammary lipogenesis in rats nursing large litters.

Histidine dose-response effects on lactational performance and plasma amino acid concentrations in lactating dairy cows: 2. Metabolizable protein-deficient diet

The objective of this experiment was to determine the effect of increasing digestible His (dHis) levels with a rumen-protected (RP) His product on milk production, milk composition, and plasma AA concentrations in lactating dairy cows fed a metabolizable protein (MP)-deficient diet, according to the National Research Council dairy model from 2001. The companion paper presents results on the effect of increasing dHis dose with a MP-adequate basal diet. Twenty Holstein cows, of which 8 were rumen-cannulated, were used in a replicated 4 × 4 Latin square design experiment with four 28-d periods. Treatments were a control diet supplying 1.8% dHis of MP or 37 g/d (dHis1.8) and the control diet supplemented RP-His to provide 2.2, 2.6, or 3.0%, dHis of MP, or 53, 63, and 74 g/d (dHis2.2, dHis2.6, and dHis3.0, respectively). Histidine dose did not affect dry matter intake, but milk yield increased quadratically and energy-corrected milk yield increased linearly with increasing dHis dose. Histidine dose had a quadratic effect on milk fat concentration but did not affect milk fat yield. Lactose concentration decreased linearly, whereas lactose yield increased linearly with increasing dHis dose. There was a tendency for a linear increase in milk true protein concentration, and milk true protein yield increased linearly with dHis dose. Further, plasma His concentration increased linearly with increasing dHis dose and calculated apparent efficiency of His utilization decreased quadratically with increasing dHis supply. Histidine had minor or no effects on rumen fermentation. In the conditions of this experiment, RP-His supplementation of an MP-deficient corn silage-based diet increased milk yield linearly up to a dHis supply of 63 g/d (or 2.6% dHis of MP) and increased feed efficiency, energy-corrected milk yield and milk true protein yield linearly up to a dHis supply of 74 g/d (or 3.0% dHis of MP) in lactating dairy cows.

Effect of feeding hydrolyzed feather meal and rumen-protected lysine on milk protein and energy utilization in late-lactation Jersey cows

Hydrolyzed feather meal (HFM) is a feed that is high in rumen undegradable protein; however, it is low in Lys compared with other high rumen undegradable protein sources. Additionally, processing methods differ by facility, which affects AA composition and protein digestibility. The objective of this study was to use lactating dairy cows to determine the effects of feeding 2 sources of HFM that differed by the amount of blood they contained and also to study the effects of supplementing rumen-protected (RP) Lys when these sources of HFM are fed. In this study, 12 multiparous Jersey cows were enrolled in a triplicated 4 × 4 Latin square with 4 periods 28 d in length. Cows were fed 2 total mixed rations that differed by source of HFM. The HFM was included at 4.5% of the diet dry matter, and one source was produced with the addition of poultry blood. Cows were randomly assigned to 1 of 4 treatment sequences. Treatments were as follows: HFM without added blood and no RP-Lys, HFM with added blood and no RP-Lys, HFM without blood and with RP-Lys (22 g of digestible Lys), and HFM with added blood and RP-Lys. The source of HFM containing blood tended to increase dry matter intake (18.3 vs. 17.3 ± 0.72 kg/d), and increased milk yield (20.5 vs. 18.4 ± 1.31 kg/d) and protein yield (0.788 vs. 0.694 ± 0.040 kg/d). The inclusion of RP-Lys did not affect milk or protein yield. In cows fed HFM containing blood, plasma concentration of Lys (82.1 vs. 70.8 ± 4.06 μM) and His (27.8 vs. 17.9 ± 3.15 μM) was higher. The addition of RP-Lys had no effect on the concentration of either plasma Lys or His. Gross energy intake tended to increase for HFM containing more blood (81.4 vs. 77.3 ± 3.29 Mcal/d); however, no difference was observed for intake of digestible energy (52.0 ± 2.20 Mcal/d) or metabolizable energy (46.4 ± 2.02 Mcal/d). Similar to dry matter intake, N intake increased with the inclusion of HFM containing blood, but crude protein digestibility decreased (61.6 vs. 66.0%). Results of this study highlight that source of HFM can be a factor that affects milk production and that this in part is due to differences in the profile of AA. Additionally, the observation that plasma His and milk protein increased with the consumption of HFM containing more blood suggests that His may have played a role in increasing milk and milk protein yield.

Muscle metabolome and adipose tissue mRNA expression of lipid metabolism-related genes in over-conditioned dairy cows differing in serum-metabotype

Over-conditioned dairy cows, classified by body condition score (BCS) and backfat thickness (BFT) are less able to metabolically adapt to the rapidly increasing milk yield after parturition. Based on serum metabolome and cluster analyses, high BCS cows (HBCS) could be classified into metabotypes that are more similar to normal (NBCS) cows, i.e., HBCS predicted normal (HBCS-PN) than the HBCS predicted high (HBCS-PH) cows—similar to the concept of obese but metabolically healthy humans. Our objective was to compare muscle metabolome and mRNA abundance of genes related to lipogenesis and lipolysis in adipose tissue between HBCS-PH (n = 13), HBCS-PN (n = 6), and NBCS-PN (n = 15). Tail-head subcutaneous fat was biopsied on d −49, 3, 21, and 84 relative to parturition. Potential differences in the oxidative capacity of skeletal muscle were assessed by targeted metabolomics in M. semitendinosus from d 21. Besides characteristic changes with time, differences in the mRNA abundance were limited to lipogenesis-related genes on d −49 (HBCS-PH > HBCS-PN). The HBCS-PH had more than two-fold higher muscle concentrations of short (C2, C4-OH, C6-OH) and long-chain acylcarnitines (C16, C18, and C18:1) than HBCS-PN, indicating a greater oxidative capacity for fatty acids (and utilization of ketones) in muscle of HBCS-PN than HBCS-PH cows.