• Asian-Australasian Journal of Animal Sciences
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• 제29권12호
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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.

• Asian-Australasian Journal of Animal Sciences
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• 제19권12호
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• pp.1742-1748
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• 2006

The experiment was conducted on 264 crossbred Karan-Fries (Holstein Friesian${\times}$Tharparkar) cows, over one year to explore the possibility of using milk urea (MU) concentration and milk protein content to monitor feeding adequacy under farm condition and to investigate the effects of different animal factors and season on MU concentration. Individual noon (1200 to 1300 h) milk samples were collected once in every month and analysed for urea and protein contents. Representative feed samples were also collected on the same day of milk collection and were analysed for CP content. A significant positive association (p<0.01) between MU concentration and milk yield was observed. MU concentrations (mg/dl) were found to be significantly (p<0.01) higher and lower in first lactation (44.8${\pm}$0.7) and in early lactation stage (40.7${\pm}$0.5), respectively. Average MU values were found to be significantly (p<0.01) higher in winter (50.7${\pm}$0.3) and lower in summer (32.9${\pm}$0.6). During the investigation, of the total MU observations, 50.3% were within the range of 30 to 50 mg/dl, 21.4% were <30 mg/dl and only 7.5% were >60 mg/dl. MU concentration was found to be associated significantly (p<0.05) with CP content of forages rather than concentrate. A close positive association (p<0.01) between MU level and daily milk protein (DMP) yield was observed during the investigation. The regression equation, DMP yield (g) = -24.6+33.5 daily milk yield (kg) +0.9 MU (mg/dl) was developed to establish the reference level of DMP yield. The result indicates that the effect of parity and stage of lactation may be ignored while interpreting MU values. However, reference MU values may be standardised separately for high milk yielders as level of milk yield contributes significantly to the variation of MU. The study revealed that the MU values together with DMP yield and milk protein content could be used as a potential non-invasive pointer to monitor feeding adequacy in dairy cows under farm conditions.

• Animal Bioscience
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• 제35권1호
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• pp.13-21
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• 2022

Objective: The aim of the study was to evaluate the influence of gene polymorphisms and nongenetic factors on the somatic cell score (SCS) in the milk of Holstein (n = 148) and Simmental (n = 73) cows and their crosses (n = 6). Methods: The SCS was calculated by the formula SCS = log₂(SCC/100,000)+3, where SCC is the somatic cell count. Polymorphisms in the casein alpha S1 (CSN1S1), beta-casein (CSN2), kappa-casein (CSN3), beta-lactoglobulin (LGB), acyl-CoA diacylglycerol transferase 1 (DGAT1), leptin (LEP), fatty acid synthase (FASN), stearoyl CoA desaturase 1 (SCD1), and 1-acylglycerol-3-phosphate O-acyltransferase 6 (AGPAT6) genes were genotyped, and association analysis to the SCS in the cow's milk was performed. Further, the impact of breed, farm, year, month of the year, lactation stage and parity on the SCS were analysed. Phenotype correlations among SCS and milk constituents were computed by Pearson correlation coefficients. Results: Only CSN2 genotypes A¹/A² were found to have significant association with the SCS (p<0.05), and alleles of CSN1S1 and DGAT1 genes (p<0.05). Other polymorphisms were not found to be significant. SCS had significant association with the combined effect of farm and year, lactation stage and month of the year. Lactation parity and breed had not significant association with SCS. The phenotypic correlation of SCS to lactose content was negative and significant, while the correlation to protein content was positive and significant. The correlations of SCS to fat, casein, nonfat solids, urea, citric acid, acetone and ketones contents were very low and not significant. Conclusion: Only CSN2 genotypes, CSN1S1 and DGAT1 alleles did show an obvious association to the SCS. The results confirmed the importance of general quality management of farms on the microbial milk quality, and effects of lactation stage and month of the year. The lactose content in milk reflects the health status of the udder.

• 한국식품영양과학회지
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• 제14권1호
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• pp.47-50
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• 1985

한국인 중류층 수유부들로부터 분만 후 70일까지 채취한 유즙의 인 지방질의 자방산 조성이 수유기간의 경과에 어떻게 변화하는지 살펴보았다. 8 : 0 은 이행유 단계에서, 그리고 10 : 0, 12 : 0, 14 : 0 등은 성숙유 I단계에서 각각 유의하게 증가하였다. w6계 대사산물들(20 :2w6, 20 : 4w6, 22 : 4w6)은 수유기간의 경과에 따라 점진적인 감소의 경향을 나타내었다. 24 : 1w9는 이행유 단계에서 유의한 증가의 수준을 유지하다가 그 이후는 초유 수준 이하로 유의하게 감소하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권6호
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• pp.895-899
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• 2002

Lysozyme activity in buffalo milk in relation to the period of lactation, parity of animal, weather conditions and udder infections was studied. Effect of storage and heat processing of milk on lysozyme activity was determined. Lysozyme activity was higher in buffalo milk than in cow milk. Buffalo colostrum showed lysozyme activity 5 times of that in mature milk. Lysozyme activity in buffalo milk was not influenced by the parity of animal and the stage of lactation, however, it increased during extreme whether conditions (winter and summer). Lysozyme in both cow and buffalo milk exhibited maximum activity at pH 7.4. Buffalo milk lysozyme was fully stable while the cow milk lysozyme was partly inactivated by pasteurization (low temperature-long time as well as high temperature-short time treatments). Lysozyme in buffalo milk was more stable than in cow milk during storage and heat treatment. A 10 to 50-fold increase in milk lysozyme activity was observed in mastitic cows. An assay of lysozyme activity in milk can be used to diagnose mastitis in cattle but not in buffaloes. Some buffaloes exhibited 1000 fold greater lysozyme activity and moderately raised somatic cell count in milk, but there was no sign of mastitis in these animals. A possible role of milk lysozyme in prevention of mastitis in buffaloes is discussed.

• 한국초지조사료학회지
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• 제5권3호
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• pp.180-186
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• 1985

본(本) 시험(試驗)은 옥수수와 sorghum식물(植物)에서 생육시기(生育時期) 및 환경온도(環境溫度)가 Weender성분(成分) 및 Net Energy Lactation 에 미치는 영향(影響)을 구명(究明)코자 옥수수의 Biizzard와 sorghum hybrids와 Pioneer931 및 Sioux를 공시품종(供試品種)으로 하여 뮌헨대학교초지연구소(大學校草地硏究所)에서 포장(圃場) 및 phytotron시험(試驗)으로 실시(實施)하였다. Phytotron의 주(晝)/야간(夜間) 실내온도(室內溫度)는 30/25, 25/20, 28/18 및 $18/8^{\circ}C$로 하였으며 일조(日照)는 35,000Lux로 13시간(時間) 조사(照謝)하였다. 1978-'81년간(年間) 얻어진 결과(結果)를 요약(要約)하면 다음과 같다. 1. 옥수수 및 sorghum의 crude protein은 3 엽기유식물(葉期幼植物)의 경우 각각(各各) 31.4% 및 33.9%에 이르나 생육(生育)이 진전(進展)됨에 따라 급속도(急速度)로 하락(下落)되어 출수기(出穗期)에는 9.0%(옥수수) 및 10.4% (sorghum)로 감소(減少)된다. 식물체내의 protein축적(蓄積)과 LWR 및 LAR간(間)에는 높은 정(正)(+)의 상관(相關)이 있다.($P{\leq}0.1%$). 2. 조섬유(粗纖維)의 합성(合成) 및 축적(蓄積)은 유수형성기(幼穗形成期)에서 지엽출현기(止葉出現期)에 본격적(本格的)으로 이루어지며 그 함량(含量)은 출수기(出穗期)에 각각(各各) 옥수수 28.4% 및 Sorghum 31.5%로 최고농도수집(最高濃度水準)에 달한다. 그러나 옥수수의 경우 조섬유(粗纖維) 함량(含量)은 종자(種子)가 성숙(成熟)됨에 따라 다시 감소(減少)되어 황숙기(黃熟期)에는 19.5%까지 감소(減少)되는데 반(反)해 sorghum 식물(植物)에서는 계속적(繼續的)으로 증가(增加)하는 경향(傾向)이 있다. 3. NEL 함량(含量)은 3 엽기(葉期)의 유식물(幼植物)에서 옥수수 5.98MJ 및 sorghum 5.64MJ/kg으로 높은 편이나 생육(生育)이 진행(進行)되는 동안 감소(減少)되어 유수(幼穗)가 형성(形成)되는 6-8 엽기(葉期)에 각각(各各) 5.82MJ(옥수수) 및 5.46MJ/kg(sorghum)으로 최저수준(最低水準)을 나타낸다. 옥수수의 NEL 함량(含量)은 그후 종자(種子)가 성숙(成熟)됨에 따라 6.70MJ(乳熟期) 및 6.94MJ/kg(完熟期)까지 증가(增加)되는데 비해 sorghum에서는 증가폭(增加幅)이 완만하여 계속(繼續) 낮은 수준(水準)을 유지(維持)한다. 4. 옥수수 및 sorghum식물(植物)의 NEL가치(價値)는 fruetosan, mono- 및 disaccharose등 non-structural carbo-hydrate의 합성(合成) 및 축적형태(蓄積形態)에 의(依)해 큰 영향(影響)을 받으면 NEL함량(含量)과 cell-wall constituents간(間)에는 부(負)(-)의 상관(相關)이 있다.($P{\leq}0.01%$). 5. NEL 및 starch value 환경온도(環境溫度)가 상승(上昇)됨에 따라 감소(減少)된다. 4 엽기(葉期) sorghum식물(植物)의 환경온도(環境溫度)를 달리 하였을 때 NEL가치(價値)는 각각(各各) 4.87MJ($30/25^{\circ}C$), 5.46MJ($25/20^{\circ}C$) 및 5.81MJ/kg($18/8^{\circ}C$)로 변(變)하여 고온(高溫)에서 net energy lactation 축적(蓄積)이 크게 감소(減少)되었다.

• Asian-Australasian Journal of Animal Sciences
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• 제24권2호
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• pp.230-238
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• 2011

Effects of cooling and supplemental recombinant bovine somatotropin (rbST) on hemato-biochemical characteristics were studied at different stages of lactation of crossbred Holstein Friesian cows in a tropical environment. Ten primiparous cows were divided into two groups of five animals each. The first group was housed as the non-cooled animals in an open-sided barn with a tiled roof in a normal shaded house (NS), while the second group was housed as cooled cows in an open-sided barn with a tiled roof under misty fan cooling (MFC). Three injections with rbST (500 mg per dose) at each stage of lactation (early, mid and late lactation) significantly increased total milk yield as compared with pretreatment in both cooled and non-cooled cows. Milk fat was significantly increased, while total solids, solid not fat, milk protein and lactose were not affected by the rbST treatment. Hematological parameters, plasma proteins, albumin, glucose, triglyceride, cholesterol, creatinine, alkaline phosphatase (ALP), plasma inorganic phosphate and the activities of plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were not affected by supplemental rbST in cooled and non-cooled cows. Supplementation of rbST caused a significant decrease in plasma urea concentration, while plasma FFA concentrations significantly increased in both cooled and non-cooled cows. The results of the present study suggest that exogenous rbST is efficacious in increasing milk yield without adverse effects on lactating crossbred Holstein cows in a tropical environment.

• Animal Bioscience
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• 제37권2호
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• pp.173-183
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• 2024

Objective: This study aimed to evaluate whether the methane (CH₄) to carbon dioxide (CO₂) ratio (CH₄/CO₂) and methane-related traits obtained by the sniffer method can be used as indicators for genetic selection of Holstein cows with lower CH₄ emissions. Methods: The sniffer method was used to simultaneously measure the concentrations of CH₄ and CO₂ during milking in each milking box of the automatic milking system to obtain CH₄/CO₂. Methane-related traits, which included CH₄ emissions, CH₄ per energy-corrected milk, methane conversion factor (MCF), and residual CH₄, were calculated. First, we investigated the impact of the model with and without body weight (BW) on the lactation stage and parity for predicting methane-related traits using a first on-farm dataset (Farm 1; 400 records for 74 Holstein cows). Second, we estimated the genetic parameters for CH₄/CO₂ and methane-related traits using a second on-farm dataset (Farm 2; 520 records for 182 Holstein cows). Third, we compared the repeatability and environmental effects on these traits in both farm datasets. Results: The data from Farm 1 revealed that MCF can be reliably evaluated during the lactation stage and parity, even when BW is excluded from the model. Farm 2 data revealed low heritability and moderate repeatability for CH₄/CO₂ (0.12 and 0.46, respectively) and MCF (0.13 and 0.38, respectively). In addition, the estimated genetic correlation of milk yield with CH₄/CO₂ was low (0.07) and that with MCF was moderate (-0.53). The on-farm data indicated that CH₄/CO₂ and MCF could be evaluated consistently during the lactation stage and parity with moderate repeatability on both farms. Conclusion: This study demonstrated the on-farm applicability of the sniffer method for selecting cows with low CH₄ emissions.

• Asian-Australasian Journal of Animal Sciences
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• 제13권10호
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• pp.1347-1352
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• 2000

The objectives of the study were to examine non-genetic factors that influence somatic cell counts in dairy cattle and to estimate the genetic parameters of somatic cell counts. A total of 34, 097-test day somatic cell count records were obtained from the Zimbabwe Dairy Services Association (ZDSA). The data were from 5, 615 Holstein daughters of 390 sires and 2, 541 dams tested between May 1994 and December 1998. First lactation cows contributed 22, 147 records to the data set, while 11, 950 records were from second and later parity cows. The model for analysis included fixed effects of month of calving, year of calving, stage of lactation, calving interval and test date. Milk yield and age on test day were fitted in the model as covariates. The additive genetic effects pertaining to cows, sires and dams and the residual error were the random effects. The Average Information Restricted Maximum Likelihood algorithm was used for analysis. The heritability of somatic cell scores was low at $0.027{\pm}0.013$ for parity one cows and $0.087{\pm}0.031$ for parity two and above. Repeatability estimates were $0.22{\pm}0.01$ and $0.30{\pm}0.01$ for the two lactation groups, respectively. Genetic and phenotypic correlations between the somatic cell scores and test day milk production were small and negative. It seems that there is no genetic link between somatic cell counts and milk yield in Holstein cattle in Zimbabwe. The results also seem to indicate that somatic cell count is a trait that is mainly governed by environmental factors.

• Asian-Australasian Journal of Animal Sciences
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• 제14권12호
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• pp.1712-1718
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• 2001

An experiment was carried out to study the effect of monensin administration on mammary functions in crossbred Holstein cattle. Fourteen non-pregnant late lactating crossbred Holstein cattle, approximately 270 days postpartum, were selected for the experiment. They were divided into two groups of 7 animals each. Seven animals in the treated group were given sodium monensin orally in a slow-release capsule. Animals in both control and treated groups were fed the similar diet to maintain milk production and body score at 2.5. Rice straw was fed as a source of dietary fiber throughout the experimental period. After monensin administration, a significant increase in the molar percent of ruminal propionate (p<0.05) and a significant decrease in the molar percent of ruminal acetate (p<0.05) were apparent in comparison to the pretreated period. The ratio of acetate to propionate concentration decreased significantly after monensin administration (p<0.05), while it was maintained at the similar level throughout the period of experiment in the control group. Monensin did not affect the molar percent of ruminal butyrate and valerate. The concentration of milk allantoin between the control group and monensin treated group was not different. An excretion rate of allantoin in milk decreased in animals treated with monensin (p<0.05). Mammary blood flow did not show significant difference between control and monensin treated groups. The plasma glucose concentration, arteriovenous concentration difference and mammary gland uptake of glucose remained constant in both groups. Milk yield of the later stage of lactation in the control group declined during lactation advance while a tendency to increase in the milk yield was apparent after 21 days monensin administration. Milk compositions for concentration of lactose, fat and protein in both control group and monensin treated group did not change throughout the experimental periods. From these results, it can be concluded that the action of monensin could affect the ruminal fermentation pattern. Monensin could not increase milk yield in the late lactating period.