• Asian-Australasian Journal of Animal Sciences
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• v.3 no.3
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• pp.247-252
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• 1990

Nine Holstein cows in mid lactation period were utilized to examine the effect of recombinant bovine somatotropin (BST) of tow companies (Company A, Company B) on milk production and milk composition under the feeding conditions of Korea. Treatments were 0 (Control), 25 mg BST/day from company A (BST A) and 25 mg BST/day from company B (BST B) injected subcutaneously, once daily beginning at $200{\pm}20$ days postpartum and continuing for 28 days. Cows were fed ad libitum a total mixed diet throughout the experimental period. BST treatments increased average 4% fat corrected milk yields and milk energy output over the 28-day treatment period. However, no differences were observed in dry matter intake, gross efficiency, energy intake and percent milk energy. Although there was a tendency for increased milk fat percent, there were no differences in milk composition and yields of major milk components except for milk fat yield with BST injection. Somatic cells of all groups were also characteristic of a well managed herd. Neither mean body condition score nor body weight was significantly (p <0.05) changed before and during BST treatment. BST concentration in milk remained in the range of control animals throughout the experimental period of BST treatment. Results indicate that short-term injection of recombinant bovine somatotropin from two companies to lactating dairy cow resulted in similar increased in milk yield without alteration of major milk components or feed intake.

• Asian-Australasian Journal of Animal Sciences
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• v.2 no.3
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• pp.418-420
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• 1989

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.5
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• pp.627-631
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• 2006

The objective of this study was to evaluate the association of genetic differences in the bovine leptin gene and milk yield, reproduction, body condition score (BCS), and plasma glucose level in Iranian Holstein cows. In total, two hundred and thirty eight cows were used and genotyped for a restricted fragment length polymorphism at the leptin gene locus. Two genotypes, AA and AB, have been distinguished which have the frequencies of 0.89 and 0.11, respectively. The genotypes were distributed according to the Hardy - Weinberg equilibrium ($x^2$ = 0.733). During the first 12 wk of lactation, milk yield and composition, live weight, BCS and plasma glucose were measured in 50 cows. Data were analyzed based on a repeated measures ANOVA. During this period, milk yield and composition, live weight, BCS and plasma glucose level were similar among the genotypes. The first cumulative 60-d milk yield, 305-d milk yield, days to first breeding, days open and days from first breeding to conception using previous lactation records were also analyzed using Standard Least Square within mixed models. Fixed effects were year, season, parity and age at calving, and sire. For the reproductive traits the cumulative first 60-d milk yield was also added to the model. Animal was fitted as a random effect. A significant association was detected between the RFLP-AB genotype and 305-d milk yield (p<0.05). The first 60-d cumulative milk yield was similar for the two genotypes (p = 0.21) and tended to be higher in the heterozygous cows. The heterozygous genotypes at the above mentioned locus had a trend to better reproductive performance than the homozygous. The results demonstrate that the RFLP B-allele can yield a higher 305-d milk production with a trend to better reproductive performance.

• Food Science of Animal Resources
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• v.26 no.1
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• pp.121-126
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• 2006

Major milk proteins have considerable variane which comes from substitution and deletions in their amino arid sequences. Variants in genes that code for milk proteins, such as ${\beta}$-lactoglobulin (${\beta}-LG$) have been established as genetic markers for milk production and milk protein composition in dairy cattle. The effect of ${\beta}-LG$ variant on milk production traits, such as milk yield. fat yield, protein yield, fat percentage and protein percentage, was estimated for 482 Holstein cows in the first lactation. The ${\beta}-LG$ variants were determined by PCR-RFLP technique at the DNA level. Single trait linear model was used for the statistical analysis of the data. Results of this study indicated that ${\beta}-LG$ variants affected significantly protein yield (p<0.05) and fat percentage (p<0.05). Animals with the AA variant produced 31kg of milk protein more than animals with the BB variant. On the contrary, cows with the BB variant had fat percentage higher by 0.35 and 0.32% compared with cows with the AA and AB variants, respectively. No associations between the ${\beta}-LG$ variants and milk yield, protein percentage and fat yield were found Therefore, milk production traits could be improved through ${\beta}-LG$ typing by increasing the frequency of A variant for protein yield or the frequency of B variant for fat content in Holstein dairy cattle population.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.4
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• pp.528-530
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• 2002

The study was designed to evaluate the seasonal influences on cross-bred cow milk composition and paneer yield in Dhauladhar mountain range of sub-himalayan region. Fifty samples from each season were collected from a herd of $Jersey{\times}Red\;Sindhi{\times}Local$ cross-bred cows during summer (April-June), rainy (July-September) and winter (November-February) and analyzed for fat, total solids (TS) and solids not fat (SNF). Paneer was prepared by curdling milk at $85{\pm}2^{\circ}C$ with 2.5 per cent citric acid solution. Overall mean for fat, TS and SNF content of milk and paneer yield were 4.528, 13.310, 8.754 and 15.218 per cent respectively. SNF and TS content varied among seasons being highest in winter (8.983% and 13.639%) followed by summer (8.835% and 13.403%) and lowest in rainy season (8.444% and 12.888%). Paneer yield was lowest (14.792%) in rainy season and highest (15.501%) in winter season.

• Asian-Australasian Journal of Animal Sciences
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• v.28 no.10
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• pp.1449-1453
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• 2015

The objective of the present study was to determine the effects of feeding pelletized broccoli byproducts (PBB) on milk yield and milk composition in dairy cows. In Trial 1, an in vitro gas test determined the optimal replacement level of PBB in a concentrate mixture in a mixed substrate with Chinese wild ryegrass hay (50:50, w/w) at levels of 0, 10%, 20%, 30%, or 40% (dry matter basis). When the concentrate was replaced by PBB at a level of 20%, no adverse effects were found on the gas volume or its rate constant during ruminal fermentation. In trial 2, 24 lactating cows (days in milk = $170.4{\pm}35$; milk yield = $30{\pm}3kg/d$; body weight = $580{\pm}13kg$) were divided into 12 blocks based on day in milk and milk yield and randomly allocated to two dietary treatments: a basic diet with or without PBB replacing 20% of the concentrate mixture. The feeding trial lasted for 56 days; the first week allowed for adaptation to the diet. The milk composition was analyzed once a week. No significant difference in milk yield was observed between the two groups (23.5 vs 24.2 kg). A significant increase was found in milk fat content in the PBB group (p<0.05). Inclusion of PBB did not affect milk protein, lactose, total solids or solids-not-fat (p>0.05). These results indicated that PBB could be included in dairy cattle diets at a suitable level to replace concentrate mixture without any adverse effects on dairy performance.

• Animal Bioscience
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• v.35 no.10
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• pp.1499-1511
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• 2022

Objective: This 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. Methods: The 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. Results: The 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. Conclusion: Both 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.

• Food Science of Animal Resources
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• v.25 no.3
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• pp.328-332
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• 2005

The effect of k-casein (k-CN) variant on milk production traits (milk yield, fat yield, protein yield, fat percentage and protein percentage) was estimated for 568 Holstein cows in the first lactation. The k-CN valiant were determined by PCR-RFLP (restriction fragment length polymorphism) technique at the DNA level. Single trait linear model was used for the statistical analysis of the data. Result of this study indicated that k-CN variant affected significantly milk yield (P<0.05) and protein yield (P<0.01). Animals with the BB variant produced 622kg milk more and had protein yield higher by 32kg compared with animals with the AA variant No associations between the k-CN variants and other milk production trait were found. Therefore, milk and protein yield may be improved through milk protein typing by increasing the frequencies of k-CN B variant in dairy cattle population. In cheese making, it will be also preferable to have milk with the B variant of k-CN, which gives higher yield having a better quality than the A variant milk.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.12
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• pp.1705-1711
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• 2014

The objective of this study was to evaluate the effect of ruminally protected amino acids (RPAAs) and ruminally protected fat (RPF) supplementation on ruminal fermentation characteristics (in vitro) and milk yield and milk composition (in vivo). Fourteen mid-lactating Holstein dairy cows (mean weight $653{\pm}62.59kg$) were divided into two groups according to mean milk yield and number of days of postpartum. The cows were then fed a basal diet during adaptation (2 wk) and experimental diets during the treatment period (6 wk). Dietary treatments were i) a basal diet (control) and ii) basal diet containing 50 g of RPAAs (lysine and methionine, 3:1 ratio) and 50 g of RPF. In rumen fermentation trail (in vitro), RPAAs and RPF supplementation had no influence on the ruminal pH, dry matter digestibility, total volatile fatty acid production and ammonia-N concentration. In feeding trial (in vivo), milk yield (p<0.001), 4% fat corrected milk (p<0.05), milk fat (p<0.05), milk protein (p<0.001), and milk urea nitrogen (p<0.05) were greater in cows fed RPAAs and RPF than the corresponding values in the control group. With an index against as 0%, the rates of decrease in milk yield and milk protein were lower in RPAAs and RPF treated diet than those of basal diet group (p<0.05). In conclusion, diet supplemented with RPAAs and RPF can improve milk yield and milk composition without negatively affecting ruminal functions in Holstein dairy cows at mid-lactating.

• Asian-Australasian Journal of Animal Sciences
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• v.24 no.6
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• pp.800-809
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• 2011

The objective of this study was to investigate the effects of different ratios of corn silage (CS): alfalfa hay (AH), and extruded soybeans (ESB) on milk yield, milk composition, blood metabolites, and fatty acids in milk fat and plasma. Ninety multiparous Holstein cows were arranged in a randomized block design experiment which lasted 14 weeks. Treatments were arranged as a $3{\times}3$ factorial with 0%, 5% or 10% ESB (dry matter basis) and three forage treatments: I) 30% CS, 10% AH and 10% Leymus chinense hay (LC); ii) 20% corn silage, 20% alfalfa hay and 10% LC; iii) 10% CS, 30% AH and 10% LC. Cows were allowed to consume a total mixed ration ad libitum. There was no change of dry matter intake when cows were fed the experimental diets. As more AH was added to the diets, milk yield, milk protein content and yield, and trans9, cis11-conjugated linoleic acids (CLA) concentrations in milk fat and plasma increased. When ESB were supplemented to the diets, milk yield, and trans9, cis11-CLA concentration in milk fat and plasma increased. When 10% ESB was added to the diet containing 30% AH the trans9, cis11-CLA content (1.46 g/100 g of total fatty acids) in milk was the highest among all treatments. These results suggests that AH could replace part of a CS diet and be a good forage source of diet for dairy cows to improve milk yield and milk composition. Meanwhile, ESB could be included in the diet with high AH to improve production performance of dairy cows.