• Korean Journal of Veterinary Service
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• v.42 no.2
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• pp.67-71
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• 2019

A variety of livestock feed resources were used in Korean dairy farm due to a lack of the endemic feed. However, there is inadequate real farm data to support farmers' decisions on the choice of options. The main objective of this study was to evaluate the nutritional value of total mixed ration (TMR) as well as the metabolic diseases status in Korean dairy farms. TMR samples were collected from nine feed companies and eight selected self-formulated by the dairy farms. The nutrient contents were examined by AOAC methods. The frequency of metabolic diseases such as ketosis and hypocalcemia were surveyed. The average moisture content was 36.2% although the min. and max. value were varied from 21.7% and 50.6% among farms. The mean${\pm}$standard deviation of crude fiber (CF), crude ash (CA), ether extract (EE), and crude protein (CP) were $21.4{\pm}2.5$, $4.6{\pm}0.4$, $3.2{\pm}0.5$ and $9.8{\pm}1.7$, respectively. However, the average ADF and NDF was $17.3{\pm}3.7$ and $31.0{\pm}5.7$, respectively. The compositions of TMR were varied significantly among the dairy farms. The frequency of clinical Ketosis (CK), subclinical ketosis (SCK) and hypocalcemia were higher in early lactation period with 4.5%, 11.0% and 3.0%, respectively. Also, the frequency of SCK was higher than CK and hypocalcemia throughout the lactation. Periodic TMR nutrient analysis based on herd production or physiology change would maximize the effects of TMR feeding. Furthermore, the study results would be useful to the farm practitioner and producer for their farm management.

• Animal Bioscience
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• v.37 no.4
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• pp.576-590
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• 2024

Objective: The objective of this study was to identify genes associated with 305-day milk yield (MY) and fat yield (FY) that also influence the adaptability of the Thai multibreed dairy cattle population to tropical conditions. Methods: A total of 75,776 imputed and actual single nucleotide polymorphisms (SNPs) from 2,661 animals were used to identify genomic regions associated with MY and FY using the single-step genomic best linear unbiased predictions. Fixed effects included herd-year-season, breed regression, heterosis regression and calving age regression effects. Random effects were animal additive genetic and residual. Individual SNPs with a p-value smaller than 0.05 were selected for gene mapping, function analysis, and quantitative trait loci (QTL) annotation analysis. Results: A substantial number of QTLs associated with MY (9,334) and FY (8,977) were identified by integrating SNP genotypes and QTL annotations. Notably, we discovered 17 annotated QTLs within the health and exterior QTL classes, corresponding to nine unique genes. Among these genes, Rho GTPase activating protein 15 (ARHGAP15) and catenin alpha 2 (CTNNA2) have previously been linked to physiological traits associated with tropical adaptation in various cattle breeds. Interestingly, these two genes also showed signs of positive selection, indicating their potential role in conferring tolerance to trypanosomiasis, a prevalent tropical disease. Conclusion: Our findings provide valuable insights into the genetic basis of MY and FY in the Thai multibreed dairy cattle population, shedding light on the underlying mechanisms of tropical adaptation. The identified genes represent promising targets for future breeding strategies aimed at improving milk and fat production while ensuring resilience to tropical challenges. This study significantly contributes to our understanding of the genetic factors influencing milk production and adaptability in dairy cattle, facilitating the development of sustainable genetic selection strategies and breeding programs in tropical environments.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.1
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• pp.1-6
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• 2010

The objectives of this study were to i) investigate genetic performance for linear type traits of individual Holstein dairy cows, especially focusing on comparative traits, and to estimate genetic variances for these traits using actual data, and ii) compare genetic performance and improvement of progeny by birth country of the cows. Linear type traits defined with five comparative traits on this study were general stature composite (GSC), dairy capacity composite (DCC), body size composite (BSC), foot and leg composite (FLC), and udder composite (UDC). These traits were scored from 1 to 6 with 1 = poor, 2 = fair, 3 = good, 4 = good plus, 5 = very good and 6 = excellent. Final scores (FS) were also included in this study. Data used was collected from the years 2000 to 2004 by the Korea Animal Improvement Association (KAIA). Only data of more than five tested cows by herd appraisal date and by sires having more than ten daughters were included to increase the reliability of the data analyses. A total of 30,204 records of the selected traits, which was collected from 26,701 individuals having pedigree information were used. Herd appraisal date, year of age, lactation stage (grouped by month), and time lagged for milking (in hours) were assumed as fixed effects on the model. Animal additive genetic effects considering pedigree relationship and residual errors were assumed with random effects. Year of age at appraisal date was classified from one to nine years of age, assigning the value of nine years of age for animals that were greater than or equal to nine years of age. From our results, the estimate for heritability was 0.463, 0.346, 0.473, 0.290, and 0.430 on GSC, DCC, BSC, FLC and UDC, respectively. The estimate for FS heritability was 0.539. The greatest breeding values for GSC were estimated for Canada, with the breeding values for American lines increasing for 10 years starting in 1989 but tending to decrease after that until 2004. For DCC, the breeding values for American and Canadian lines showed similar patterns until 1999, after which the breeding values for the American lines declined sharply. For BSC, data from Korea, Canada and the USA followed similar trends overall except when the breeding values of the American lines decreased starting in 1999. Overall, the methods used to evaluate genetic performance in this study were acceptable and allowed for the discovery of differences by country of genetic origin, likely due in part to the American use of selection indexes based primarily on milk yield traits until methods for evaluating other traits began to emerge.

• Asian-Australasian Journal of Animal Sciences
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• v.26 no.9
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• pp.1237-1246
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• 2013

The objective of this study was to estimate variance components and genetic parameters for lactation milk yield (LY), lactation length (LL), average milk yield per day (YD), initial milk yield (IY), peak milk yield (PY), days to peak (DP) and parameters (ln(a) and c) of the modified incomplete gamma function (MIG) in an Ethiopian multibreed dairy cattle population. The dataset was composed of 5,507 lactation records collected from 1,639 cows in three locations (Bako, Debre Zeit and Holetta) in Ethiopia from 1977 to 2010. Parameters for MIG were obtained from regression analysis of monthly test-day milk data on days in milk. The cows were purebred (Bos indicus) Boran (B) and Horro (H) and their crosses with different fractions of Friesian (F), Jersey (J) and Simmental (S). There were 23 breed groups (B, H, and their crossbreds with F, J, and S) in the population. Fixed and mixed models were used to analyse the data. The fixed model considered herd-year-season, parity and breed group as fixed effects, and residual as random. The single and two-traits mixed animal repeatability models, considered the fixed effects of herd-year-season and parity subclasses, breed as a function of cow H, F, J, and S breed fractions and general heterosis as a function of heterozygosity, and the random additive animal, permanent environment, and residual effects. For the analysis of LY, LL was added as a fixed covariate to all models. Variance components and genetic parameters were estimated using average information restricted maximum likelihood procedures. The results indicated that all traits were affected (p<0.001) by the considered fixed effects. High grade $B{\times}F$ cows (3/16B 13/16F) had the highest least squares means (LSM) for LY ($2,490{\pm}178.9kg$), IY ($10.5{\pm}0.8kg$), PY ($12.7{\pm}0.9kg$), YD ($7.6{\pm}0.55kg$) and LL ($361.4{\pm}31.2d$), while B cows had the lowest LSM values for these traits. The LSM of LY, IY, YD, and PY tended to increase from the first to the fifth parity. Single-trait analyses yielded low heritability ($0.03{\pm}0.03$ and $0.08{\pm}0.02$) and repeatability ($0.14{\pm}0.01$ to $0.24{\pm}0.02$) estimates for LL, DP and parameter c. Medium heritability ($0.21{\pm}0.03$ to $0.33{\pm}0.04$) and repeatability ($0.27{\pm}0.02$ to $0.53{\pm}0.01$) estimates were obtained for LY, IY, PY, YD and ln(a). Genetic correlations between LY, IY, PY, YD, ln(a), and LL ranged from 0.59 to 0.99. Spearman's rank correlations between sire estimated breeding values for LY, LL, IY, PY, YD, ln(a) and c were positive (0.67 to 0.99, p<0.001). These results suggested that selection for IY, PY, YD, or LY would genetically improve lactation milk yield in this Ethiopian dairy cattle population.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.6
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• pp.905-911
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• 2002

A study was carried out to assess the therapeutic effect of ascorbic acid in mastitis of dairy cows. The herd with a population of 250-275 lactating cows was screened for clinical and subclinical mastitis for a period of 5 months. Based on inclusion and exclusion criteria, eighteen animals each with clinical and subclinical mastitis in one quarter only were selected as study population. Twelve cows (group A) with normal udder and health were also selected as a healthy control. Clinical mastitis cows were grouped as B (n=12) and C (n=6). Cows of group B were treated with ascorbic acid at 25 mg/kg, subcutaneously for 5 consecutive days and intramammary infusion (Ampicillin sodium 75 mg and Cloxacillin sodium 200 mg/infusion) based on antibiotic sensitivity test, till complete recovery. Group C cows received only intramammary infusion till the complete recovery. Eighteen subclinical mastitis cows were divided in group D (n=12) and E (n=6). Cows of group D were treated with ascorbic acid at 25 mg/kg subcutaneously for 5 consecutive days while group E did not receive any treatment. California mastitis test (CMT), somatic cell count (SCC), physical changes of udder and milk were used to diagnose and classify the mastitis. Evaluation of the therapy was based on CMT score and physical changes of udder and milk. Sample size calculation was also performed but was not followed for control groups due to scarcity of cases. Adequate blinding was done when and where required to avoid the biases. Confounding variables like herd, age of the cow, stage of the lactation, season and geographical region were duly considered and adequate blocking was followed. Ascorbic acid was administered in clinical and subclinical cases even after cure considering its immunostimulatory and healing inducing effects. The recovery rate was faster in cases of clinical mastitis treated with ascorbic acid along with an intramammary infusion (group B) than the quarters of group C cows. Quarter wise the average duration/number (3.16${\pm}$0.11 days) of antimicrobial intramammary infusion was significantly (p<0.01) less in group B than that of average duration/number (5.33${\pm}$0.20 days) of group C. Subclinical mastitis cows treated with ascorbic acid showed 83.33% recovery while 16.77% did not respond to treatment till last day of study. Cows of group E (untreated) did not recovered from the mastitis. Subjective parameters viz. swelling, pain reflex of udder and physical changes in milk from quarter of ascorbic acid treated cows (group B) disappeared earlier than that of group C cows. It is concluded from this study that the ascorbic acid might be useful as an adjunct in case of clinical mastitis to get quick recovery with less number of intramammary infusions. High recovery rate in subclinical mastitis quarters of group D cows is appreciable and opens a new avenue to conduct further trials in a larger population in various field conditions. However, the pharmacology of ascorbic acid with particular reference to health of mammary gland needs to be investigated.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.9
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• pp.1216-1222
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• 2012

Somatic cells count (SCC), milk yield (MY) and pedigree information of 2,791 first lactation cows that calved between 1990 and 2010 on 259 Thai farms were used to estimate genetic parameters and trends for SCC and its genetic association with MY. The SCC were log-transformed (lnSCC) to make them normally distributed. An average information-restricted maximum likelihood procedure was used to estimate variance components. A bivariate animal model that considered herd-yr-season, calving age, and regression additive genetic group as fixed effects, and animal and residual as random effects was used for genetic evaluation. Heritability estimates were 0.12 (SE = 0.19) for lnSCC, and 0.31 (SE = 0.06) for MY. The genetic correlation estimate between lnSCC and MY was 0.26 (SE = 0.59). Mean yearly estimated breeding values during the last 20 years increased for SCC (49.02 cells/ml/yr, SE = 26.81 cells/ml/yr; p = 0.08), but not for MY (0.37 kg/yr, SE = 0.87 kg/yr; p = 0.68). Sire average breeding values for SCC and MY were higher than those of cows and dams (p<0.01). Heritability estimates for lnSCC and MY and their low but positive genetic correlation suggested that selection for low SCC may be feasible in this population as it is in other populations of dairy cows. Thus, selection for high MY and low SCC should be encouraged in Thai dairy improvement programs to increase profitability by improving both cow health and milk yield.

• Asian-Australasian Journal of Animal Sciences
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• v.15 no.7
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• pp.963-967
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• 2002

Eighteen crossbred goats were selected from the Institute's goat herd to determine the changes in hormones, blood metabolites and yield and composition of milk during lactation. The blood and milk samples were collected from each goat in a heparinized vacutainer tubes at fortnightly interval for a period of 150 days. In milk samples, fat, protein and lactose contents were estimated while in blood plasma hormones viz., prolactin, GH, cortisol, insulin, $T_4$ and $T_3$ were measured using radioimmunoassay methods. The plasma concentration of prolactin, GH and cortisol were high during early lactation when the goats acquired peak milk yield. During remainder of lactation their concentration varied. The high NEFA concentration during early lactation indicated mobilization of body reserves as the body weights also decrease during early lactation. However, with the advancement of lactation, the body weights of the goats and the concentration of NEFA declined which indicated utilization of NEFA for energy yielding purposes in addition to fatty acid synthesis. The ambient temperatures did not influence plasma concentration of prolactin, GH, insulin, $T_3$ and $T_4$ during the lactation cycle. The fat content of milk varied significantly (p<0.01) but protein and lactose content of milk remains unchanged during different stages of lactation. Growth hormone was positively correlated with insulin (p<0.05) during lactation while prolactin had a positive correlation with lactose and plasma NEFA (p<0.01) and negative correlation with $T_3$ (p<0.05).

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.9
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• pp.1387-1399
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• 2020

Objective: The objective of this study was to estimate the genetic parameters and trends for milk, fat, and protein yields in the first three lactations of Thai dairy cattle using a 3-trait,-3-lactation random regression test-day model. Methods: Data included 168,996, 63,388, and 27,145 test-day records from the first, second, and third lactations, respectively. Records were from 19,068 cows calving from 1993 to 2013 in 124 herds. (Co) variance components were estimated by Bayesian methods. Gibbs sampling was used to obtain posterior distributions. The model included herd-year-month of testing, breed group-season of calving-month in tested milk group, linear and quadratic age at calving as fixed effects, and random regression coefficients for additive genetic and permanent environmental effects, which were defined as modified constant, linear, quadratic, cubic and quartic Legendre coefficients. Results: Average daily heritabilities ranged from 0.36 to 0.48 for milk, 0.33 to 0.44 for fat and 0.37 to 0.48 for protein yields; they were higher in the third lactation for all traits. Heritabilities of test-day milk and protein yields for selected days in milk were higher in the middle than at the beginning or end of lactation, whereas those for test-day fat yields were high at the beginning and end of lactation. Genetics correlations (305-d yield) among production yields within lactations (0.44 to 0.69) were higher than those across lactations (0.36 to 0.68). The largest genetic correlation was observed between the first and second lactation. The genetic trends of 305-d milk, fat and protein yields were 230 to 250, 25 to 29, and 30 to 35 kg per year, respectively. Conclusion: A random regression model seems to be a flexible and reliable procedure for the genetic evaluation of production yields. It can be used to perform breeding value estimation for national genetic evaluation in the Thai dairy cattle population.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.12
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• pp.1689-1694
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• 2004

This study was conducted to develop a novel adjustment factors for 305 days using 138,103 lactation records and 1,770,764 daily records, which were based on environmental circumstances such as herd year, season, age at calving, dry period and lactating stages. The present study showed that the change of persistency of cows at the first parity from total lactacting characteristics was slowly processed, while it was rapidly changed in cows at the second parity stage. Particularly, there was an outstanding difference between the first and second parity cows. Milk yield and composition increased as the age at calving was increased. In addition, milk yield and composition were higher at the first parity on fall compared with others, and those were higher at the more than second parity on fall and winter compared with other parity stages and seasons. The cow of dry group was included into lactating records of more than second parity stage. The data indicated that optimal results arose from 45-70 days of dry period. Milk yield was decreased when dry period was longer or shorter than 45-70 days. The lactating days were divided into 17, 28 and 38 stages to compare the multiplicative correction factors. The factor was effective at 28 stages on the first parity. The total correlation coefficients were 0.93832, 0.95058 and 0.95076 at the present correction factor, 17 stage and 28 stage, respectively. At second parity, the factor was higher in dry group 1 and 3 at 17 stage, and it was higher in dry group 2 at 28 stage compared with others. Therefore, the present study showed that the percent squared bias (PSB), which was calculated from the novel correction factor, was better than previously used correction factors. Also, the present study indicated that the bias of the novel correction factor was improved, and this factor could be more accurate compared with others.

• Asian-Australasian Journal of Animal Sciences
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• v.29 no.12
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• pp.1682-1687
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• 2016

The objective of this study was to estimate the genetic parameters of milk protein yields in Iranian Holstein dairy cattle. A total of 1,112,082 test-day milk protein yield records of 167,269 first lactation Holstein cows, calved from 1990 to 2010, were analyzed. Estimates of the variance components, heritability, and genetic correlations for milk protein yields were obtained using a random regression test-day model. Milking times, herd, age of recording, year, and month of recording were included as fixed effects in the model. Additive genetic and permanent environmental random effects for the lactation curve were taken into account by applying orthogonal Legendre polynomials of the fourth order in the model. The lowest and highest additive genetic variances were estimated at the beginning and end of lactation, respectively. Permanent environmental variance was higher at both extremes. Residual variance was lowest at the middle of the lactation and contrarily, heritability increased during this period. Maximum heritability was found during the 12th lactation stage ($0.213{\pm}0.007$). Genetic, permanent, and phenotypic correlations among test-days decreased as the interval between consecutive test-days increased. A relatively large data set was used in this study; therefore, the estimated (co)variance components for random regression coefficients could be used for national genetic evaluation of dairy cattle in Iran.