Lactation Milk Research Articles

Exploration of allelic variants in short tandem repeats (STRs) flanking milk production QTLs and their association with milk production traits in Indian water buffaloes.

Short tandem repeats (STRs) are co-dominant, highly polymorphic marker loci, distributed throughout the genome and useful for identification and mapping of QTLs associated with variation in traits of economic significance. Allelic variants were identified in STRs located in close vicinity of cattle QTLs for milk production,, viz. BMS713, BM6404, BM4513, BM121, BM6105, TGLA245, BL1100, BMS1948, BMS711, BM1443, BM1706, BM6438, BM143, BM415, ETH131, ETH 2, and BM1329 in 109 water buffaloes of Murrah breed. All loci except TGLA245 exhibited polymorphism of varying degree. The observed number of alleles, effective number of alleles, PIC value, observed heterozygosity, and expected heterozygosity across all STR loci averaged 4.12 ± 0.22, 3.20 ± 0.22, 0.60 ± 0.04, 0.34 ± 0.05, and 0.66 ± 0.03, respectively. Goodness of fit (chi-square) and likelihood ratio (G square) test demonstrated that the population exhibited a deviation from HWE for all the loci. FIS was positive and ranged from 0.22 to 1.00. Least square analysis of variance exhibited significant effects of BM4513, ETH131, BM713, and BM6105 on first lactational total lactation milk yield, 305-day milk yield, lactation length, and dry period respectively. None of the STRs could exhibit significant effect on peak yield.

The effect of calf gender on milk lactation traits and lactation gain of Holstein and Simmental cows

Considering the challenging market conditions for dairy farms, calf gender management should be one of the tools used to increase profitability. The objective of this paper was to examine the effect of calf gender on lactation milk traits in Holstein and Simmental cows. Holstein cows that calved a female calf had a higher milk yield (p<0.0001) and lower milk fat and protein content (p<0.01) in the first lactation. The favourable effect of female calf on milk yield was also found in the second lactation of Holstein cows (p<0.0001). Simmental cows that calved female calves in the first and the second lactation also had higher milk yield and lactation gain, however the differences were not significant. Although no statistically significant effect of calf gender on milk yield was determined in the Simmental population, indications of positive effect of female calf gender on lactation milk yield impose the need for further research. Using gender selected semen as a tool for calf gender management could enable to increase the milk yield of Holstein cows and the profitability of Holstein farms as well.

EVALUASI KANDUNGAN MUTU FISIK DAN KIMIA SUSU SAPI PERAH FRIESIAN HOLSTEIN DI BPPIB TSP BUNIKASIH

Fresh milk that is good for consumption in terms of nutritional content and food safety must meet the applicable SNI. The quality of milk is largely determined by the components of substances contained in milk, including knowing the physical quality and chemical nutrient content. Research on Evaluation of Physical and Chemical Quality Content of Friesian Holstein Dairy Cows at BPPIB TSP Bunikasih was carried out in April-May 2021. The purpose of this study was to determine the physical quality of milk (color, flavor, taste, and specific gravity) and chemicals (fat, protein, and lactose) in first and second lactation FH cattle. This study uses a survey method with quantitative descriptive data analysis. The results showed that the physical quality of milk in the first lactation was yellowish-white, the characteristic flavor of milk, the sweet taste of milk, the density (BJ) of milk was 1.023 g/ml, the chemical quality of cow's milk in the first lactation was 4.86% fat content, protein 2.57%, and lactose 3.85% higher than lactation two on the physical quality of yellowish-white, distinctive aroma of milk, sweet taste of milk, density (BJ) 1.022 g/ml, the chemical quality of cow's milk in the second lactation, the fat is 4.67%, protein is 2.49%, and lactose is 3.73%. The conclusion of this study is the quality of milk in lactation one is higher than in lactation two. The physical quality of breast milk on density (BJ) still does not meet the Indonesian National Standard. The chemical qualities of milk are fat, protein, and lactose. The fat content of milk in each lactation has met the requirements of meeting the 2011 SNI, while the protein and lactose content of milk contained in BPPIB TSP Bunikasih is still below the 2011 SNI standard.

Influence of number of daughters per sire on genetic evaluation of Mehsana Buffalo bulls under field progeny testing

First lactation production records of 7,825 Mehsana buffaloes, sired by 200 sires maintained at DudhsagarResearch and Development Association, Dudhsagar Dairy, Mehsana over a period of 25 years (1989-2013), wereutilised for estimation of breeding value of the first lactation milk yield using BLUP - Univariate sire model andanimal model using WOMBAT software. The study aimed to find out the optimum number of daughters that maybe sufficient for more accurate and unbiased estimate of breeding value of Mehsana buffalo bulls. The effectivenessof different models run with different daughters per sire for sire evaluation was judged on the basis of within-sirevariance. The maximum and minimum estimated breeding values were 1924.04 l (BLUP-AM, 5 daughters/sire)and 1855.61 l (BLUP-SM, 30 daughters/sire), respectively. However, error variance estimated was highest whenfive daughters/sire were evaluated and lowest, when 30 daughters/sire were evaluated. The present study revealedthat the sire evaluation with sires having minimum 5, 10 and 15 daughters are equally efficient. However, if we doevaluation with sires having daughters more than 20, 25 or 30, additional accuracy of approximately 2.5%, 3% and5%, respectively may be obtained.

Le stress thermique chez la vache laitière Holstein de Tunisie: effets sur les performances de production

Cette étude visait à évaluer l’effet du stress thermique subis par les vaches laitières Holstein en Tunisie. Les données de contrôles laitiers : PL, MG, MP et le SCS collectés entre 2013 et 2019 chez 947 vaches dans 23 troupeaux ont été combinées avec un THI calculé à partir des données météorologiques enregistrées entre 2013 et 2019. Le modèle non linéaire de Wood a été appliqué à la modélisation de la courbe de lactation. L’analyse de la variance a été appliquée pour tester les effets de trois niveaux de THI (THI>72; 68<THI<72 et THI>72) sur la production de lait, sa composition et les paramètres de la courbe de lactation. Les résultats ont montré des pertes dues au stress thermique. Une diminution du rendement en lait et du pourcentage de matières grasses et de protéines a été signalée. Ainsi, les rendements en matières grasses et en protéines ont eu tendance à diminuer régulièrement avec l’augmentation des valeurs de THI. Le rendement laitier variait de 17,882 ± 0,064 (68 <THI <72) à 16,503 ± 0,035 kg / j (THI> 72), le pourcentage de matières grasses et de protéines variait de 3,551 ± 0,041 à 3,449 ± 0,026 et de 3,246 ± 0,031 à 3,113 ± 0,029 % pour 68 <THI <72 et THI> 72, respectivement. Les modèles de score somatique ont été marqués par une augmentation (de 4,143 à 4,358) aux plages les plus élevées de THI> 72, et des valeurs diminuées (de 4,143 à 3,857) aux plages les plus basses de THI. L’effet du THI était très significatif (P <0,05) pour tous les paramètres de la courbe de lactation et du rendement laitier. Les rendements laitiers de pointe les plus élevés et le rendement total le plus élevé de 305 jours de lactation (Y305) ont été atteints par des vaches exposées au THI entre 68 et 72.

Feasibility of Supplying Ruminally Protected Lysine and Methionine to Periparturient Dairy Cows on the Efficiency of Subsequent Lactation.

The objective of this study was to evaluate the effects of supplying ruminally protected Lys (RPL) and ruminally protected Met (RPM) to transition cows' diets on the efficiency of subsequent lactation. A total of 120 prepartum Holstein cows were assigned into four treatments blocked by the anticipated calving date, previous lactation milk yield, number of lactations, and body condition score and fed either RPL, RPM, or the combination (RPML) or control diet (CON) throughout the transition period (3 weeks before till 3 weeks after calving). From 22 to 150 days in milk (DIM), all animals (100 cows) were fed a combination of RPM and RPL (0.17% RPM and 0.41% RPL of DM; n = 25 cows/treatment) as follows; CON–RPML, RPM–RPML, RPL–RPML, and RPML–RPML. Milk production and dry matter intake (DMI) were measured daily; milk and blood samples were taken at 21, 30, 60, 90, 120, and 150 DIM. Supplemented amino acids (AA) were mixed with the premix and added to the total mixed ration during the experiment. DMI (p < 0.001) and energy-corrected milk (ECM, p = 0.04) were higher for cows that were fed RPML–RPML than other cows. Compared with CON–RPML, yields of milk total protein, lactose, and nitrogen efficiency were increased (p < 0.01), whereas milk urea nitrogen (MUN; p = 0.002) was decreased for other treatments. However, supplemental AA did not affect milk lactose percentage, fat yield, feed efficiency, or serum total protein concentration (p > 0.10). Transition cows that consumed AA had a greater peak of milk yield (p < 0.01), as well as quickly reached the peak of milk (p < 0.004). There were differences in β-hydroxybutyrate concentration during the early lactation, with a lower level for AA groups (p < 0.05), and the difference faded with the progression of lactation (p > 0.10). Fertility efficiency as measured by pregnancy rate was improved by supplemental AA during the perinatal period (p < 0.05). In conclusion, transition cows consumed RPM and RPL, increased post-calving DMI, milk production, milk protein yield, nitrogen efficiency, and improved fertility performance.

Estimation of the genetic parameters for Somatic Cell Scores in the first lactation of Romanian Black and White cattle

Abstract The aim of study was the estimation of the genetic parameters of somatic cell score of Romanian Black and White cattle population. Test-day records of somatic cell count (SCC) of 305 days lactation were from Romanian Black and White cattle population from experimental farm of our institute. The mean of somatic cell count of milk in the first lactation of Romanian Black and White cows was 291966.89. The genetic parameters were estimates with random regression test-day animal model. The heritability for somatic cell score (SCS) ranged from 0.0473 to 0.147. The breeding values for the best cows for somatic cell score were between -35.566 and -191.358. The genetic correlations between somatic cell count milk records test-day were positive. The phenotypic and genetic correlations between somatic cell count and milk yield were negative.

Regulation of Tight Junctions by Sex Hormones in Goat Mammary Epithelial Cells.

Simple SummaryHow ovarian hormones affect goat lactation by regulating cell–cell junctions is still unclear. Through the in vivo and in vitro assays, we found that ovarian hormones could elevate cell–cell junction protein expression, which may affect the intercellular space and molecule transportation between the goat mammary epithelial cells. Our assessment suggests that ovarian hormones may affect goat milk production by regulating the cell–cell junction protein expression between mammary epithelial cells.The sex hormones of estrogen and progesterone (P4) play a vital role in mammary gland development and milk lactation in ruminants. The tight junction (TJ) between adjacent secretory epithelial cells is instrumental in establishing the mammary blood–milk barrier. However, whether estrogen and P4 exert their effect on mammary function via regulating TJ remain unclear. Here, to clarify the role of 17-β estradiol (E2) and P4 in the regulation of TJ in goat mammary gland, we first explored the relationships between the concentrations of E2, P4, and the protein expression of claudin-1, claudin-3, occludin, and ZO-1 during the mammary gland development in goat. Then, we further explored the mRNA and protein expression of claudin-1, claudin-3, occludin, and ZO-1 in the goat mammary epithelial cells (GMECs) in vitro under different concentrations of E2 and P4. The results demonstrated that the protein expression of claudin-1 decreased, but occludin and ZO-1 increased with the decline in E2 and P4 during the transition from pregnancy to lactation. In the in vitro studies, E2 exerted a positive effect on the mRNA expression of claudin-1, and accelerated the proteins’ expression of claudin-1 and ZO-1 in GMECs; P4 upregulated the mRNA expression of claudin-1, claudin-3, occludin, and ZO-1, and also improved the protein expression of claudin-1, claudin-3, and ZO-1 in the GMECs. The results demonstrated that E2 and P4 play an important role in regulating the expression of the mammary TJ components, which may ultimately affect the mammary gland development and milk lactation.

Inputs for optimizing selection platform for milk production traits of dairy Sahiwal cattle.

The premises for the potential success of molecular breeding is the ability to identify major genes associated with important dairy related traits. The present study was taken up with the objectives to identify single nucleotide polymorphism (SNP) of bovine MASP2 and SIRT1 genes and its effect on estimated breeding values (EBVs) and to estimate genetic parameters for lactation milk yield (LMY), 305-day milk yield (305dMY), 305-day fat yield (305dFY), 305-day solid not fat yield (305dSNFY) and lactation length (LL) in Sahiwal dairy cattle to devise a promising improvement strategy. Genetic parameters and breeding values of milk production traits were estimated from 935 Sahiwal cattle population (1979-2019) reared at National Dairy Research Institute at Karnal, India. A total of 7 SNPs, where one SNP (g.499C>T) in exon 2 and four SNPs (g.576G>A, g.609T>C, g.684G>T and g.845A>G) in exon 3 region of MASP2 gene and 2 SNPs (g.-306T>C and g.-274G>C) in the promoter region of SIRT1 gene were identified in Sahiwal cattle population. Five of these identified SNPs were chosen for further genotyping by PCR-RFLP and association analysis. Association analysis was performed using estimated breeding values (n = 150) to test the effect of SNPs on LMY, 305dMY, 305dFY, 305dSNFY and LL. Association analysis revealed that, three SNP markers (g.499C>T, g.609T>C and g.-306T>C) were significantly associated with all milk yield traits. The estimates for heritability using repeatability model for LMY, 305dMY, 305dFY, 305dSNFY and LL were low, however the corresponding estimates from first parity were 0.20±0.08, 0.17±0.08, 0.13±0.09, 0.13±0.09 and 0.24, respectively. The repeatability estimates were moderate to high indicating consistency of performance over the parities and hence reliability of first lactation traits. Genetic correlations among the traits of first parity were high (0.55 to 0.99). From the results we could conclude that optimum strategy to improve the Sahiwal cattle further would be selecting the animals based on their first lactation 305dMY. Option top include the significant SNP in selection criteria can be explored. Taken together, a 2-stage selection approach, select Sahiwal animals early for the SNP and then on the basis of first lactation 305dMY will help to save resources.

A Study on the Changes of Colostrum Quality, Milk Constituents and Somatic Cell Count after Calving in Holstein Friesian Cows

Colostrum quality produced by dairy cows varies considerably. The amount of immune protein content in colostrum has also high specific gravity. In this study, the specific gravity of colostrum (SGC) produced by 32 Holstein-Friesian cows with different parities in the first five milking after calving, and additionally, the fat content (FC), non-fat dry matter content (NFDMC) and somatic cell count (SCC) in the milk samples taken in the first five milking and on the fifth and 10th day milking of lactation were determined. The effects of parity and milking order on SGC, FC, NFDMC and Log10SCC were detected to be statistically significant. Parity x milking order interaction effect was found to be significant for SGC, FC and NFDMC, but its effect on Log10SCC was insignificant. Cows with three and upper parities had higher SGC, FC, NFDMC, and Log10SCC than cows in the first and second parities. While SGC (1055.09±1.20 mg/mL), FC (6.36±0.12%) and NFDMC (18.17±0.37%) obtained at the first milking decreased gradually in advancing milking, Log10SCC (5.90±0.028) level increased. The correlation coefficients of SGC with FC, NFDMC, and Log10SCC were low-medium, the coefficients between FC and NFDMC were moderately too high in the first three milking, and decreased and approached zero in advancing milking. It was observed that SGC remained high even in the fourth milking in some cows, especially in the third and higher parities. In conclusion, it has been revealed that not only colostrum obtained from the first milking, but also quality colostrum produced in subsequent milking can be used in calf feeding in dairy cattle farms. However, all this depends on the adoption of the strategy of determining the quality of colostrum with the help of a colostrometer in dairy cattle farms.

Genetic parameters of milk and lactation curve traits of dairy cattle from research farms in Thailand.

ObjectiveThis study was aimed to estimate the genetic parameters, including genetic and phenotypic correlations, of milk yield, lactation curve traits and milk composition of Thai dairy cattle from three government research farms.MethodsThe data of 25,789 test-day milk yield and milk composition records of 1,468 cattle from lactation 1 to 3 of Holstein Friesian (HF) and crossbred HF dairy cattle calved between 1990 and 2015 from three government research farms in Thailand were analysed. 305-day milk yield was estimated by the Wood model and a test interval method. The Wood model was used for estimating cumulative 305-day milk yield, peak milk yield, days to peak milk yield and persistency. Genetic parameters were estimated using linear mixed models with herd, breed group, year and season of calving as fixed effects, and animals linked to a pedigree as random effects, together with a residual error. Univariate models were used to estimate variance components, heritability, estimated breeding values (EBVs) and repeatability of each trait, while pairwise bivariate models were used to estimate covariance components and correlations between traits in the same lactation and in the same trait across lactations.ResultsThe heritability of 305-day milk yield, peak milk yield and protein percentage have moderate to high estimates ranging from 0.19 to 0.45 while days to peak milk yield, persistency and fat percentage have low heritability ranging from 0.08 to 0.14 in lactation 1 cows. Further, heritability of most traits considered was higher in lactation 1 compared with lactations 2 and 3. For cows in lactation 1, high genetic correlations were found between 305-day milk yield and peak milk yield (0.86±0.07) and days to peak milk yield and persistency (0.99±0.02) while estimates of genetic correlations between the remaining traits were imprecise due to the high standard errors. The genetic correlations within the traits across lactation were high. There was no consistent trend of EBVs for most traits in the first lactation over the study period.ConclusionBoth the Wood model and test interval method can be used for milk yield estimates in these herds. However, the Wood model has advantages over the test interval method as it can be fitted using fewer test-day records and the estimated model parameters can be used to derive estimates of other lactation curve parameters. Milk yield, peak milk yield and protein percentage can be improved by a selection and mating program while days to peak milk yield, persistency and fat percentage can be improved by including into a selection index.

Yarı entansif şartlarda yetiştirilen İvesi ırkı koyunlarda süt verimi ve süt kalite özellikleri

This research was carried out to determine milk yield and milk quality parameters of Awassi sheep raised under semi-intensive conditions in Harran University Experimental Animal Research and Application Center. In the study, 2 and 3 years old, 46 heads of Awassi sheep were used as animal material. The care and feeding of the ewes were made in a way that the Animal Research and Application Center routinely applied. Average daily milk yield in Awassi sheep was determined as 1002.82±52.57 g. Lactation milk yield and lactation period were calculated as 168.10±8.44 kg and 166.10±2.11 days, respectively. In the study, the overall mean fat, protein, lactose and dry matter ratios were determined. % 6.27±0.10; 5.12±0.05; 4.81±0.05 and 17.44 ± 0.13 respectively. Somatic cell count and pH values in Awassi sheep milk were determined as 207.56±21.29 cell/ml and 6.29±0.03 respectively. L*, a* and b* values in sheep milk were determined as 72.69±0.16; -6.11±0.04 and 6.92±0.08. respectively. It was determined that the amount of butyric acid (C4:0), which is one of the short-chain fatty acids, was higher than the values reported for sheep milk in all groups examined in the study. As a result, it has been determined that there is a wide variation in milk yield in Awassi sheep. A rapid genetic improvement may be achieved by utilizing this variation.

Factors affecting fertility traits and milk yield of Holstein cattle with different origins raised in Trakya region

This study was conducted with Holstein heifers imported from the United States (US), Germany, and the Czech Republic to a private dairy farm in Kırklareli/Lüleburgaz region in Turkey to evaluate their adaptation in terms of milk production and fertility performance. The first insemination age of the herd was 490.62 days, and the first calving age was 804.24 days. The number of inseminations required per pregnancy was calculated as 3.99, gestation length as 279.72 days, and service period as 213.99 days. The rate of abortion and twin births were higher in those of US origin. Increased first calving age was observed in heifers of German origin due to delayed insemination. The mean actual lactation milk yield in the first lactation periods was 11834.75 Lt, 305 days milk yield was 8573.31 Lt, lactation length was 419.61 days, the dry period was 63.02 days. Milk yield performance of Holsteins of US origin was higher in the first lactation period. In conclusion, milk production was profitable; however, the fertility performance of the herd was poor in general. Poor fertility performance was due to poor herd management and adaptation problems. Therefore, after the calving period, more attention should be paid to oestrus monitoring and insemination activities. In Turkey, the success of live animal imports should be well investigated; in particular, problems occurring during animal selection for importation should be evaluated, and short-/long-term national strategies should be developed.

Lifelong Impact? The Effect of Phototherapy Admission on Future Breastfeeding.

Lifelong Impact? The Effect of Phototherapy Admission on Future Breastfeeding.

Profile of Twenty-Three Human Milk Oligosaccharides in Han Chinese Mothers throughout Postpartum 1 year

Human milk oligosaccharides (HMOs) are multifunctional carbohydrates in breast milk, which are composed by a variety of structures. This study aimed to identified HMOs concentration profile, milk microbiota composition, and the associations with major maternal characteristics in Han Chinese mothers in the one-year lactation period. Seventeen healthy mothers aged from 28 to 36 years, who gave birth to healthy term infants, were recruited. Carbohydrates were detected using the MIRIS human milk analyzer (HMA), and twenty-three HMOs were quantified using ultra-performance liquid chromatography-triple quadrupole mass spectrometry (UPLC-MS). Results showed that carbohydrates were relatively stable, while total HMO concentrations ranged from 1.74 to 9.72 g/L and decreased gradually over lactation in breast milk. Based on the structure, seven sialylated HMOs concentration showed the significant decline (p&lt;0.05) after three months in lactation. In addition, the relationships between maternal factors, containing the lactation period, genetic status, delivery mode, parity, and milk microbiota profile, and the HMO composition in healthy women, which still need further investigations, were observed.

Breeding objectives for dairy cattle under low, medium and high production systems in the tropics

A deterministic bio-economic model was developed to estimate economic weights for genetic improvement of lactation milk yield, fat yield, age at first calving, calving interval, mature weight and survival under low, medium and high production systems in the Tropics. Input parameters were obtained from dairy production systems in Kenya which has a tropical environment. The highest proportion of revenue is from the sale of milk followed by sale of heifers, cull cows and sale of male calves under all production systems. On the other hand, feed cost is the most important production cost followed by labour, marketing, reproduction and health costs, respectively. Economic values for the six traits were derived from a profit equation using revenue and production costs per cow per year. The economic values were then discounted using diffusion coefficients which account for differences between traits in the time when the improvement is expressed. Economic weights were robust to changes in input and output prices, changes in feeding strategies, and changes in milk and surplus heifer marketing strategies. Genetic standard deviations were multiplied by economic values to standardise the economic value of traits and to compare their potential for economic response. When expressed as proportion of their sum, these relative economic weights under the low, medium and high production systems for lactation milk yield were 51.36, 59.79 and 63.98%; for fat yield 4.50, 10.69 and 9.05%; for age at first calving 3.16, 2.66 and 0.55%; for calving interval 33.59, 19.88 and 20.05%; for mature weight 1.55, 1.34 and 1.19% and for survival rate 5.84, 5.64 and 5.18%, respectively. The predicted responses followed the same pattern as the relative economic weights. This shows that milk yield and calving interval were most important in all production systems but the value of response for traits differed between production systems with more emphasis on milk yield and less on calving interval in the high production systems. Moderate correlations were estimated between the breeding objective for the low, medium and high production systems. To maximise response in the overall breeding objective, different selection criteria are required for the three production systems.

Early life indicators of first lactation milk yield and the effect of treatment for bovine respiratory disease on survivability and risk of pregnancy in Holstein dairy cattle

The primary objective of this study was to evaluate the long-term effects of variables that could be measured early in life on first lactation milk production. The secondary objective was to evaluate the long-term effects of treatment for bovine respiratory disease (BRD), within the first 120 days of life, on survivability to 850 days and reproductive success. Data from Holstein heifer calves was collected from 1 October, 2015–31 January, 2020 and included milk consumption (MC; n = 10,431), bodyweight (BW; n = 9,825), average daily gain (ADG; n = 6,194), heifer conception age (n = 10,112), and 305-day first lactation milk production (305 M; n = 5,823), and treatment records for BRD (n = 12,485). Calves were fed pasteurized whole milk through an automated calf feeding system for 60 days (range, 48 – 126 days), with a 30% crude protein (CP) and 5% crude fat enhancer added at 20 g/L milk. Calves were weighed at birth, weaning, and several other times prior to 2 years of age. Daily BW were predicted for individual animals using a third order orthogonal polynomial to model individual BW regressions. Daily BW predictions were used to calculate ADG and BW predictions on specific days of interest.Season born, ADG (0–400 days), milk production potential, and heifer conception age had a significant impact on 305-day first lactation milk production (all P ≤ 0.05; r2 = 0.31). A retrospective cohort study was conducted utilizing data collected from a commercial farm with cohorts defined by BRD status. Calves treated for BRD from 61 to 120 days old had a significantly lower chance of survival to 850 days of age than animals not treated for BRD. Additionally, calves treated for BRD from 61 to 120 days old had reduced risk of pregnancy. The results show the impact of early life on future milk production, survivability, and pregnancy risk on a commercial dairy herd.

Milk yield, composition, and lactation curve models of Bargur cattle under farmers' production system in their native habitat.

Milk yield and composition traits (fat (%) and SNF (%)) from 1229 test day records of 205 Bargur cattle maintained under a farmers' production system were studied. This breed is known for its adaptability to the hilly tracts of Erode District in Tamil Nadu. Performance recording was done in the natural habitat through the test-day milk yield from lactating cows in the farmers' herds. Effects of non-genetic factors like season, year, parity, stage of lactation, and days from calving were studied using mixed models with animal taken as a random effect. Estimated marginal means for daily milk yield (DMY, L/day), fat (%), and SNF (%) were 2.05 ± 0.03, 4.08 ± 0.03%, and 8.19 ± 0.01%, respectively. Stage of lactation was highly significant (P < 0.01) for DMY, fat, and SNF. Season and year were significant for DMY and SNF, where higher productivity was obtained in the monsoon season, but fat remained constant in all the seasons. Parity was significant (P < 0.05) only for SNF, and year was significant for DMY (P < 0.01) and SNF (P < 0.05). Persistency was 5.9% calculated using Wood's gamma function and 63.0% calculated using the ratio of predicted yields. This was slightly lower compared to dairy breeds of cattle. Thirteen different lactation curve models were used for fitting of Bargur cattle lactation curve, and the Parabolic exponential model was the best fitting model based on model diagnostic criteria.

Genetic analysis of skin measurements and its relation with milk production in Murrah buffaloes reared under tropical conditions of Chhattisgarh plains.

The experiment was conducted at ABIS Buffalo Dairy Farm, Rajnandgaon, on 300 milking Murrah buffaloes. In buffaloes, the information on body measurements, skin thickness, and their associations with milk yield and interrelationship among them is scanty. Hence, the present study was designed to establish the relationship of skin thickness with milk production in Murrah buffaloes. The data was statistically analyzed using R statistical software. The average skin thickness of the neck, chest, abdomen, rump, hind quarter, udder, and flank regions were 6.27 ± 0.11, 6.13 ± 0.13, 7.28 ± 0.14, 9.78 ± 0.15, 8.00 ± 0.12, 4.14 ± 0.09, and 8.53 ± 0.12mm, respectively. In this study, the skinfold thickness of the neck and chest regions had a highly significant effect (P < 0.01) on the total lactation milk yield of Murrah buffaloes whereas skin thickness of other regions under study had no significant effect on total lactation milk yield. The results of the study revealed that parity and stage of lactation had a significant effect (P < 0.05) on the skinfold thickness of all the seven regions of Murrah buffalo under investigation. The study indicated that except for the udder region the correlation of all skin thickness with TMY was found to be negative and significant. The genetic correlations between milk yield and skin thickness of the neck, abdomen, and udder were low to medium. The heritability estimate for different skinfold thicknesses and milk yield in this study was low to medium. These results could facilitate further exploration in the use of skinfold thickness for management precision and can be useful in the selection of better animals under field conditions.

Effects of calving year, season, and age on some lactation traits of Anatolian buffaloes reared at farmer conditions in Turkey

The aim of this study was to investigate the effects of some environmental factors like calving year, season, buffalo cow age and village on some milk yield traits of Anatolian buffaloes, such as daily milk yield for lactation length (MYLL), total lactation milk yield (TLMY), lactation length (LL), and daily milk yield for calving interval (MYCI). 1838 milk yield records obtained from 851 Anatolian buffaloes reared under different environmental conditions from 2015 through 2019 within the scope of the Bartın Anatolian Buffalo Breeding Project were assessed. The least square means and standard errors for MYLL, TLMY, LL, and MYCI were 4.07  0.02 kg, 1078.6  7.54 kg, 263.83  1.16 days, and 2.75  0.03 kg, respectively. As a result of the study, the effects of village, calving year and age (P&amp;lt;0.001) and calving season (P&amp;lt;0.05) on MYLL; village, calving year and age (P&amp;lt;0.001) on TLMY; village, calving year and age (P&amp;lt;0.001) and calving season (P&amp;lt;0.05) on MYCI; calving age, village (P&amp;lt;0.001) and calving year (P&amp;lt;0.05) on LL were found statistically significant. Moreover, high positive phenotypic correlations between TLMY and MYLL (r = 0.78, P&amp;lt;0.001) and LL and TLMY (r = 0.67, P&amp;lt;0.001) were estimated. The results revealed that milk production traits might be improved by considering calving season and age in breeding studies and stud-selection programs in Anatolian buffaloes. Besides, it will remarkably contribute to the number of limited studies that have focused on this breed.