Hisato Takeda

Age-related changes in gene expression of the growth hormone secretagogue and growth hormone-releasing hormone receptors in Holstein-Friesian cattle.

Growth hormone secretion from the anterior pituitary gland is controlled by interactions between three hormone receptors, between GHRH and GHRH receptor (GHRH-R), between ghrelin and growth hormone secretagogue receptor (GHS-R1a), and between somatostatin and somatostatin receptors in the hypothalamus and anterior pituitary gland. Ghrelin-GHS-R1a is involved in many important functions, including GH secretion and appetite. We investigated age-related changes in the expressions of GHS-R1a, GHS-R1b (the truncated-type receptor), and GHRH-R mRNAs by real-time reverse transcription-PCR using 16 tissues, leukocytes, oocytes, and cumulus cells in Holstein-Friesian cattle. The tissue samples were divided into three age classes: 1) 19 to 26 d of age (preweaning calves), 2) 2 mo to 6.5 mo of age (postweaning calves), and 3) 3.2 to 8.1 yr of age (cows). The GHS-R1a mRNA was highly (P < 0.05) expressed in the arcuate nucleus, pituitary gland, and liver compared with that of the other tissues in all age classes. Expression of GHS-R 1a mRNA in the arcuate nucleus of postweaning calves was > 10-fold greater (P < 0.01) than those of preweaning calves and cows, and its expression level was the greatest (P < 0.01) in all tissues examined in age group 2. GHS-R1a and GHRH-R mRNA expressions in the pituitary gland of preweaning calves tended to be greater (P < 0.20 and P < 0.17, respectively) than those of postweaning calves and cows. GHS-R1b mRNA expression was detected in all tissues examined, and abundance was greater (P < 0.05) in the pancreas, pituitary gland, spleen, arcuate nucleus, adipose tissue, and leukocyte compared with that of the other tissues examined in age group 3. Interestingly, a relatively large animal-to-animal variation was observed in pancreas GHS-R 1b mRNA expression. The GHRH-R mRNA was markedly increased (P < 0.01) in the pituitary gland in all age groups compared with that of the other tissues. GHRH-R mRNA abundance in the arcuate nucleus, pituitary gland, liver, spleen, adipose tissue, and heart of preweaning calves tended to be greater than those of postweaning calves and cows. The GHRH-R mRNA was not detected in the mammary gland and adipose tissue of nonlactating cows.

Relationship between the lactation curve and udder disease incidence in different lactation stages in first-lactation Holstein cows

We examined the relationships between the shape of the first parity lactation curve and udder disease incidence at different stages of lactation in 538 Holstein cows. Data used were first-parity daily milk yields and treatment records. Each cow was classified according to whether or not it had had udder disease at least once over the whole lactation period or in one of three stages within the lactation period. We then examined the differences in the shapes of the lactation curves between the disease incidence and non-incidence group in each stage. Cows that had high rates of increase in milk yield and high milk yields in early lactation were predisposed to udder disease afterwards. Cows with high milk production over a long period but with low lactation persistency were predisposed to udder disease after the peak of lactation. There was no difference in total milk yield between incidence and non-incidence groups in all stages, suggesting that, for a comparable level of lactation, cows without udder diseases have flatter lactation curves.

Genetic analysis of the cumulative pseudo-survival rate during lactation of Holstein cattle in Japan by using random regression models

Longevity is a crucial economic trait in the dairy farming industry. In this study, our objective was to develop a random regression model for genetic evaluation of survival. For the analysis, we used test-day records obtained for the first 5 lactations of 380,252 cows from 1,296 herds in Japan between 2001 and 2010; this data set was randomly divided into 7 subsets. The cumulative pseudo-survival rate (PSR) was determined according to whether a cow was alive (1) or absent (0) in her herd on the test day within each lactation group. Each lactation number was treated as an independent trait in a random regression multiple-trait model (MTM) or as a repeated measure in a random regression single-trait repeatability model (STRM). A proportional hazard model (PHM) was also developed as a piecewise-hazards model. The average (± standard deviation) heritability estimates of the PSR at 365 d in milk (DIM) among the 7 data sets in the first (LG1), second (LG2), and third to fifth lactations (LG3) of the MTM were 0.042±0.007, 0.070±0.012, and 0.084±0.007, respectively. The heritability estimate of the STRM was 0.038±0.004. The genetic correlations of PSR between distinct DIM within or between lactation groups were high when the interval between DIM was short. These results indicated that whereas the genetic factors contributing to the PSR between closely associated DIM would be similar even for different lactation numbers, the genetic factors contributing to PSR would differ between distinct lactation periods. The average (± standard deviation) effective heritability estimate based on the relative risk of the PHM among the 7 data sets was 0.068±0.009. The estimated breeding values (EBV) in LG1, LG2, LG3, the STRM, and the PHM were unbiased estimates of the genetic trend. The absolute values of the Spearmans rank correlation coefficients between the EBV of the relative risk of the PHM and the EBV of PSR at 365 DIM for LG1, LG2, LG3, and the STRM were 0.75, 0.87, 0.91, and 0.93, respectively. These results indicated that the EBV of PSR could predict the genetic contribution to survival. The EBV based on the PSR of the STRM was highly correlated with that of the MTM (0.83-0.96). Furthermore, the calculation load of the STRM was lighter than that of the MTM because the rank of the matrix of the STRM was smaller than that of the MTM. These results indicated that the STRM is an appropriate model for estimating survivability by using random regression models.

Genetic analysis of fat‐to‐protein ratio, milk yield and somatic cell score of Holstein cows in Japan in the first three lactations by using a random regression model

We estimated the genetic parameters of fat-to-protein ratio (FPR) and the genetic correlations between FPR and milk yield or somatic cell score in the first three lactations in dairy cows. Data included 3,079,517 test-day records of 201,138 Holstein cows in Japan from 2006 to 2011. Genetic parameters were estimated with a multiple-trait random regression model in which the records within and between parities were treated as separate traits. The phenotypic values of FPR increased soon after parturition and peaked at 10 to 20 days in milk, then decreased slowly in mid- and late lactation. Heritability estimates for FPR yielded moderate values. Genetic correlations of FPR among parities were low in early lactation. Genetic correlations between FPR and milk yield were positive and low in early lactation, but only in the first lactation. Genetic correlations between FPR and somatic cell score were positive in early lactation and decreased to become negative in mid- to late lactation. By using these results for genetic evaluation it should be possible to improve energy balance in dairy cows.

Prediction of random-regression coefficient for daily milk yield after 305 days in milk by using the regression-coefficient estimates from the first 305 days

Objective Because lactation periods in dairy cows lengthen with increasing total milk production, it is important to predict individual productivities after 305 days in milk (DIM) to determine the optimal lactation period. We therefore examined whether the random regression (RR) coefficient from 306 to 450 DIM (M2) can be predicted from those during the first 305 DIM (M1) by using a RR model. Methods We analyzed test-day milk records from 85,690 Holstein cows in their first lactations and 131,727 cows in their later (second to fifth) lactations. Data in M1 and M2 were analyzed separately by using different single-trait RR animal models. We then performed a multiple regression analysis of the RR coefficients of M2 on those of M1 during the first and later lactations. Results The first-order Legendre polynomials were practical covariates of RR for the milk yields of M2. All RR coefficients for the additive genetic (AG) effect and the intercept for the permanent environmental (PE) effect of M2 had moderate to strong correlations with the intercept for the AG effect of M1. The coefficients of determination for multiple regression of the combined intercepts for the AG and PE effects of M2 on the coefficients for the AG effect of M1 were moderate to high. The daily milk yields of M2 predicted by using the RR coefficients for the AG effect of M1 were highly correlated with those obtained by using the coefficients of M2. Conclusion Milk production after 305 DIM can be predicted by using the RR coefficient estimates of the AG effect during the first 305 DIM.

Genetic correlations between the cumulative pseudo-survival rate, milk yield, and somatic cell score during lactation in Holstein cattle in Japan using a random regression model

Trends in genetic correlations between longevity, milk yield, and somatic cell score (SCS) during lactation in cows are difficult to trace. In this study, changes in the genetic correlations between milk yield, SCS, and cumulative pseudo-survival rate (PSR) during lactation were examined, and the effect of milk yield and SCS information on the reliability of estimated breeding value (EBV) of PSR were determined. Test day milk yield, SCS, and PSR records were obtained for Holstein cows in Japan from 2004 to 2013. A random subset of the data was used for the analysis (825 herds, 205,383 cows). This data set was randomly divided into 5 subsets (162-168 herds, 83,389-95,854 cows), and genetic parameters were estimated in each subset independently. Data were analyzed using multiple-trait random regression animal models including either the residual effect for the whole lactation period (H0), the residual effects for 5 lactation stages (H5), or both of these residual effects (HD). Milk yield heritability increased until 310 to 351 d in milk (DIM) and SCS heritability increased until 330 to 344 DIM. Heritability estimates for PSR increased with DIM from 0.00 to 0.05. The genetic correlation between milk yield and SCS increased negatively to under -0.60 at 455 DIM. The genetic correlation between milk yield and PSR increased until 342 to 355 DIM (0.53-0.57). The genetic correlation between the SCS and PSR was -0.82 to -0.83 at around 180 DIM, and decreased to -0.65 to -0.71 at 455 DIM. The reliability of EBV of PSR for sires with 30 or more recorded daughters was 0.17 to 0.45 when the effects of correlated traits were ignored. The maximum reliability of EBV was observed at 257 (H0) or 322 (HD) DIM. When the correlations of PSR with milk yield and SCS were considered, the reliabilities of PSR estimates increased to 0.31-0.76. The genetic parameter estimates of H5 were the same as those for HD. The rank correlation coefficients of the EBV of PSR between H0 and H5 or HD were greater than 0.9. Additionally, the reliabilities of EBV of PSR of H0 were similar to those for H5 and HD. Therefore, the genetic parameter estimates in H0 were not substantially different from those in H5 and HD. When milk yield and SCS, which were genetically correlated with PSR, were used, the reliability of PSR increased. Estimates of the genetic correlations between PSR and milk yield and between PSR and SCS are useful for management and breeding decisions to extend the herd life of cows.

Live Body Volume and Density Measuring Method for Estimation of Carcass Traits in Japanese Black Steers by Computer Image Analysis

40頭の黒毛和種去勢牛に対する3方向からの画像(後,横および上方向)が,ビデオカメラにより記録され,コンピュータのメモリー上に取り入れられた.生体の輪郭線の抽出および生体の部分体積および部分密度の推定は,著者らにより作成されたコンピュータプログラムで行われた.生体に関する12形質,15の枝肉形質および超音波による皮下脂肪厚も測定された.それらの体測定値と画像解析形質との関連性が検討された,生体部分体積と生体部分密度の平均値はそれぞれ0.35m3,1.608g/cm3であった.生体部分体積は,体のサイズに関連する形質に対して有意かつ正に影響していた.生体部分密度と超音波による皮下脂肪厚との間に有意かつ負の相関が認められた.枝肉形質を推定するための重回帰分析に,生体部分体積および密度を取り入れることで,歩留基準値のR2値に有意な改善が認められた.

Effects of Castration on the Fatty Acid Composition of Various Tissues in the Japanese Shorthorn

牛枝肉の脂質性状に対する去勢の影響と雄牛肥育における粗飼料多給の影響を検討した.実験1では,日本短角種牛を用い,3ヵ月齢去勢(C3),8ヵ月齢去勢(C8),および無去勢すなわち雄(B1)の各区4頭ずつ配置して比較を行なった.実験2では,濃厚飼料多給(BC)と粗飼料多給(BR)の各区2頭ずつ配置して,雄牛肥育における飼養方法の違いによる影響を検討した.なお濃厚飼料給与の去勢肥育牛5頭を対照区(CC)として比較に用いた.(1) 供試した筋肉および脂肪組織から抽出した総脂質における,トリアシルグリセロール画分の脂肪酸組成に関して,雄牛では去勢牛と比べて,C18:0の割合が高く,C16:0の割合が低い傾向を示した.不飽和脂肪酸の割合には区間差がみられなかった.また同じ雄牛の肥育においては,濃厚飼料多給区の方が粗飼料多給区と比べて不飽和脂肪酸割合がやや高い傾向を示した.(2) 筋肉におけるリン脂質画分の脂肪酸組成に関しては,去勢の影響が認められなかった.これに対し飼養条件の違いによる影響は認あられ,BC区はBR区と比べて,ω3系列の脂肪酸の割合が低く,ω6系列の脂肪酸の割合が高い傾向を示した.(3) アルデヒドについては,雄牛は去勢牛と比べて,C18:0の割合が高く,C16:0の割合の値が低い傾向となった.