• 농업생명과학연구
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• 제50권5호
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• pp.173-182
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• 2016

본 연구는 분만간격과 비유곡선 모수들 간의 상관관계를 규명하기 위하여 농협중앙회 젖소개량사업소에서 진행하고 있는 유우군 능력검정사업에 참여하고 있는 홀스타인 젖소로부터 조사한 착유기록 36,505개를 분석하였는데, 분석에 이용된 착유기록은 모두 2011년부터 2013년 사이에 분만한 경산우로부터 조사하였다. 비유곡선 모수는 Wood 모형을 적용하여, SAS 9.2 NLIN Procedure를 이용해 추정하였다. 분만년도-계절(봄, 여름, 가을, 겨울)효과와 산차(2, 3, 4산차)의 효과를 고정효과로 한 다형질 일반선형모형으로 SAS(GLM procedure)를 이용하였다. 분만간격, 305일 유량, 비유곡선모수(A, b, c), 비유지속성, Peak 일시 및 Peak기 유량에 대해 분만년도-계절과 산차의 효과는 모두 유의적으로 나타났다(p<0.05). Wood 모형으로 추정한 비유곡선 함수는 2, 3 및 4산차에 대해 각각 yt=24.66t0.175e-0.00302t, yt=24.69t0.192e-0.00334t 및 yt=24.22t0.200e-0.00341t으로 추정되었다. 분만간격과 305일 유량, 모수값 A, b, c, 비유지속성, Peak 일시 및 Peak기 유량과의 표현형상관(잔차상관)은 각각 0.093, -0.014, 0.028, -0.046, 0.099, 0.085 및 0.052으로 나타났다. 분만간격이 길어지면 비유곡선의 상향경사도, 비유지속성, Peak 일시, Peak기 유량은 증가하고, 비유곡선의 하향경사도는 감소하여, 305일 유량은 증가할 것으로 판단된다.

• Asian-Australasian Journal of Animal Sciences
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• 제15권6호
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• pp.890-894
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• 2002

The accuracy of the gamma function to describe lactation curve of Yankasa ewes was investigated using milk production data obtained from 168 ewes with either complete or incomplete 84 day lactation records. Ewes were daily hand milked after over-night separation from lamb and thorough disinfection of the udder. The daily milk yield on the average was estimated from the weekly total yield. The effect of type of birth, parity, season of birth and lactation length on the components of lactation curve (a, b, c and s) were analysed by least-square procedures. All factors except parity significantly (p<0.01) influenced the curve parameters. The goodness of fit of the function did not differ between the two classes of varying duration of lactation; incomplete lactation however, showed a lower persistency and as expected lower level of production. Correlations ($r_p$) between lamb weight gain and milk yield using the weight records from lamb weighed at weekly intervals indicated a high and positive relationship in the early lactation that decreased in intensity as the lactation advanced.

• Journal of Animal Science and Technology
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• 제46권5호
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• pp.773-782
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• 2004

본 연구는 산차와 비유기가 다양한 Holstein 종 56두를 사용하여 사료섭취량과 에너지요구 량을 근거로 개체별 사료에너지요구량의 서열을 설정하고, 이를 3개 우군으로 나누어 각 우군의 상반평균치에 기준하여 자가배합사료(herdmix ration)를 조제한 후 이것을 이용한 사양체계가 비유기 및 산차에 미치는 영향을 관행 사양체계와 switch-over method로 비교하였다. 자가배합사료 급여체계는 전 비유기 동안 산유량과 유지율을 증진시켰으며(P<0.05), 산차별 생산능력도 모든 산차에서 향상되었다(P<0.05). 비유단계별 성적에서는 비유초기와 중기에서 Herd-mix구의 설제산유량(AMY) 및 지방보정유량(FCM)이 유의적으로 증가하였으나(P<0.05) 유지율은 유의차가 없었다. 비유말기에는 AMY, 유지율 및 FCM 모두 Herd-mix구가 관행구에 비하여 증가하였으며 특히 유지율과 FCM이 현저하게 증가하였다(P<0.01). Herd-mix구와 관행구의 FCM 비유지속성은 각각 93.24%와 92.69%로서 Herd-mix구의 비유지속성이 높았으며 비유곡선의 형태도 이상적 추세를 보였다. 유대와 사료비를 고려한 조수익을 산출한 결과 Herd-mix구가 관행구보다 40% 높았다. 결론적으로, 본 연구는 젖소의 에너지요구량과 사료 에너지 농도를 정확히 평가하여 우군을 편성한 후 그 상반평균을 배합목표로 설정하고 사용할원료에 대한 실질적인 평가를 근거로 배합비를 설정하는 것이 산유능력을 향상시킴과 동시에 경제적으로 유려하다는 사실을 입증하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제5권1호
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• pp.107-112
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• 1992

Feeding of bypass protein to lactating animals have been suggested by many research scientists as a way to increase the nutrient supply at the intestinal level thereby enhance animal production in ruminant animals. A feeding trial with a formulated bypass protein feed on straw based ration was carried out by using lactating cross bred cows at the stage of 4th month of their lactation. Bypass protein feed was fed at 5 different levels. Urea Molasses Block was used as a nitrogen source to the rumen microflora. In order to reduce the heat increment straw intake was restricted to all the animals. Urea Molasses Block intake was noticed varying in proportion with the bypass protein feed intake. Milk production was observed increasing in accordance with the level of bypass protein feed intake. However, the maximum response was noticed in cows that were fed 3 kg bypass protein feed. The nutrient availability at this stage was below the NRC (1988) requirements. Other remarkable finding was that the cows maintained the persistency of milk production even after 3rd month of lactation when the ambient temperature was $40^{\circ}C$.

• Asian-Australasian Journal of Animal Sciences
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• 제17권3호
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• pp.343-348
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• 2004

The objective of the present study was to determine the plasma level of insulin-like growth factor-I (IGF-I) in relation to mammary blood flow and milk yield including biological variables of relevance to milk synthesis in two different types of crossbred Holstein cattle at 3 different stages of lactation. Eight heifers were 87.5% HF and eight 50% HF animals were selected for the experiments. The three stages of lactation tested were: early lactation (30 days postpartum), mid-lactation (120 days postpartum) and late lactation (210 days postpartum). Animals in each group were fed a concentrate and rice straw treated with 5% urea as the source of roughage throughout the experiments. In early lactation, mammary blood flow and milk yield of 87.5% HF animals were significantly higher than those of 50% HF animals. In mid- and late lactation, both mammary blood flow and milk yield showed a proportional decrease from the early lactating period of 87.5% HF animals. The trends for persistency were observed in 50% HF animals as for udder blood flow and milk yield throughout the experimental periods. The plasma glucose level of the 50% HF animals was significantly higher than those of 87.5% HF animals in both early and mid-lactation. The concentrations of arterial plasma free fatty acids ($C_{16}\;to\;C_{18}$) were higher in 50% HF animals as compared with 87.5% HF animals in all periods of study. In early lactation, the concentration of plasma growth hormone (GH) of 87.5% HF animals was higher than those of the 50% HF animals, thereafter the mean level of plasma growth hormone declined in both mid- and late lactation. The concentration of plasma IGF-I of 50% HF animals was significantly higher than those of 87.5% HF animals in all stages of lactation. There were no differences among stages of lactation for the levels of plasma IGF-I, insulin and growth hormone in 50% HF animals. In 87.5% HF animals, the plasma levels of both IGF-I and insulin were lower in early lactating period while it showed an increase during mid- and late lactation. The present results indicated that the regulatory role for the higher mammary blood flow and milk yield during lactation in 87.5% HF are not mediated via the higher level of circulating IGF-I. Differences in mammary blood flow and milk yield between 50% HF and 87.5% HF animals are in part due to a higher concentration of circulating growth hormone. The lower level of circulating growth hormone in 50% HF animals would be regulated by higher levels of IGF-I, free fatty acid and glucose in plasma.

• Journal of Animal Science and Technology
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• 제47권2호
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• pp.147-158
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• 2005

The purpose of this study was to find out the effects that daughters' incomplete lactation records affect sire's breeding values through genetic evaluation using RRTDM(random regression test-day model). First, we estimated genetic parameters and breeding values on sires having complete lactation records of daughter by RRTDM, second, we changed complete lactation records of specific sires into incomplete records by various methods. Third, the breeding values were compared between complete and incomplete records. Finally, this study aimed to find out the methods to minimize the estimation errors of young bulls' breeding values. Data used in this study were collected from the dairy herd improvement program, and a total of 97,562 records were composed of 10,929 first parity with both parents known, since 1999. Breeding values on the daughters from randomly chosen sires were calculated and compared with among 90 day, 150day, and 200 day's incomplete records. For milk yields, sire's ranks of breeding values used by complete lactation records were very different from sire's ranks of breeding values obtained by incomplete lactation records(Rank_90 cut, 150cut, 200 cut).The differences were also obtained between complete lactation records(per305_full) and incomplete lactation record (per_90 cut, 150cut, 200 cut) in breeding values regarding persistency. Especially, the differences between per_90 cut and per305_full were very large(from 1.8 kg to 145kg).

• Asian-Australasian Journal of Animal Sciences
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• 제17권12호
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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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• 제9권4호
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• pp.439-447
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• 1996

Monthly test day production for 12,020 records, were collected from six of the largest specialized dairy farms located in central region of the Kingdom of Saudi Arabia. The records described lactating cows in four parities and two seasons of calving. Monthly test day records were fitted using Wood's model $At{{^b}{_e}}^{-ct}$ with multiple and additive error term. Linear and non-linear regression models were used to find the estimates of the parameters necessary to draw the lactation curves. The shape of the lactation curves of different parities showed that third lactation has the heighest peak (43.08 kg) for linear regression model and (42.08 kg) for non-linear regression model. Fourth lactation has the lowest peak (24.00kg) for linear regression model and (25.64 kg) for non-linear regression models. Cows of second and third lactations reached the peak at 58 day for both linear and non-linear regression models. Cows of first lactation were more persistent and had late peak at 68 and 67 days for both models respectively. While, third lactation cows were lower persistent and had early peak at 58 day for both models. Cows calved at winter months have higher starting values (A), higher ascending slope (b) and higher decending slope (c). Least square means of milk yield of the first four parities and for overall data were 6,653, 7,659, 7,482, 6,988 and 7,614 kg respectively. The corresponding lactation period were 358, 367, 350, 363 and 364 days respectively.

• Asian-Australasian Journal of Animal Sciences
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• 제22권12호
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• pp.1709-1717
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• 2009

This review presents a series of Key Performance Indicators (KPI) to assist Asian smallholder dairy farmers in identifying the possible causes for their poor farm performance and profitability. When assessing farm profitability, these indicators can be split into two types, those diagnosing problems with feeding management and those indicating poor herd management. As home grown forage is generally cheaper to source than purchased forage, the more produced on farm, the better. Too many stock on limited land is a common feature on Asian dairy small holdings. Unlike other classes of livestock, milking cows have very high nutrient requirements, therefore high quality forages and concentrates are essential for profitable dairying. Milk income less feed cost is one of the simplest and easy to measure indicators of farm profitability and is also quick to respond to small changes in farm practices. Problems with herd management can be diagnosed using measures such as the proportion of cows actually milking in the herd or their peak yield and persistency of production. There are also simple indicators of herd reproductive performance and of health and growth of young stock that assist in searching for the underlying causes of poor farm profitability.

• Asian-Australasian Journal of Animal Sciences
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• 제15권9호
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• pp.1364-1370
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• 2002

The objective of this study was to examine the effect of compensatory growth nutritional regimen on mammary gland growth and lactation. One hundred twenty-two Sprague Dawley female rats (35 days of age) were randomly assigned to either a control or a stair-step compensatory nutrition (SSCN) feeding regimen or an alternating 2-2-3-3-week schedule beginning with 40% energy restriction for 2 weeks followed by re-alimentation (control diet) for 2 weeks. Pup weight gain and milk yield were improved 8% and 8 to 15%, respectively, by the SSCN regimen. The gene expression of $\beta$-casein was 2.3-fold greater in the SSCN group than in the control group during early lactation, but they were greater at all stages of the second lactation. The gene expression of insulin-like growth factor-I was 40% lower in the SSCN group than in the control group during early lactation of the second lactation, but during late lactation it was 80% greater than in the control group. The concentration of serum corticosterone tended to be higher in the SSCN group during the late stage of the first lactation. These results suggest that the stair-step compensatory nutrition regimen improves lactation performance and persistency by modulation of cell differentiation and apoptotic cell death.