荷斯坦奶牛体型线性性状与产奶量的相关性分析

对新疆荷斯坦奶牛的产奶量与体型线性性状进行了相关。通径分析。结果表明，荷斯坦奶牛的乳房纵沟深，后乳房宽，后乳房高与产奶量呈中等正相关，体高，体长，尻宽，尻长与产奶量呈弱相关；后乳房宽，乳房纵沟深是直接影响产奶量的重要性状，且是正身作用；后乳房高对产奶量起负面影响。其间接作用大。     

Genotyping of groups of cows to improve genomic breeding values of new traits

Genotyping females and including them into the reference set for genomic predictions in dairy cattle is considered to provide gains in reliabilities of estimated breeding values for selection candidates. This should especially be true for low heritability traits. By the use of simulation, we extended a genomic reference set for an existing trait by including a fixed number of genotyped first‐crop daughters for one or two generations of reference sires. Moreover, we calculated results for the effects of a similar strategy in a situation where for a new trait the recording of phenotypes has recently started. For this case, we compared the effect of two different genotyping strategies: first, to phenotype cows but to genotype their sires only, and second, to collect phenotypes and genotypes on the same cows. We studied the effects on validation reliabilities and unbiasedness of predicted values for selection candidates. We found that by extending the reference set with genotyped daughters it is possible to increase the validation reliability of genomic breeding values. In the case of a new trait, it is always better to collect and use genotypes and phenotypes on the same animals instead of using only sire genotypes. We found that the benefits that can be achieved are sensitive to the sampling strategy used when selecting females for genotyping.     

Energetic efficiency of milk synthesis in dual-purpose cows grazing tropical pastures

The aim of this study was to assess the energetic efficiency of milk synthesis by grazing dual-purpose cows with or without a starch-based supplement in tropical South Mexico. Forty-six Holstein × Zebu cows were used in a 2 × 2 × 2 factorial design. Factors analysed were diet (supplemented, unsupplemented), age (young: 1–2 calvings, mature: >3 calvings) and day of lactation (21 and 84 days post-calving). The supplement represented about 30% of estimated dry matter (DM) intake. Grass intake was measured using the n-alkane technique at 21 and 84 days post-calving when calculations of efficiency were performed. Efficiency for milk synthesis was reported as feed conversion efficiency (FCE, kilograms of milk per kilogram of DM intake), gross energetic efficiency (GEE, milk energy output/metabolisable energy (ME) intake) and efficiency of ME use for lactation (k _l, adjusted to zero energy balance). There were no interactions between factors. FCE and GEE were not different between diets, but supplemented cows had a lower (p < 0.01) k _l value (0.62) than unsupplemented cows (0.67), suggesting a diverted partition of nutrients towards body tissue. Mature cows were more efficient (p < 0.001) than young cows in terms of FCE (1.13 vs 0.87) and GEE (0.34 vs 0.26), but equal in terms of k _l (0.65). FCE (1.10 vs 0.90) and GEE (0.34 vs 0.27) were both higher on day 21 compared with day 84 post-calving, with a trend for a higher k _l in early lactation. Dual-purpose cows used tropical grasses efficiently for milk synthesis, and higher milk yield observed in supplemented cows was due to a higher intake of nutrients rather than a higher energetic efficiency.     

荷斯坦奶牛体型线性性状对305天产奶量的通径分析

进行荷斯坦奶牛体型线性性状时305 d产奶量的通径分析,建立体型线性性状对305 d产奶量的最优回归方程.随机抽取荷斯坦奶牛395头,测量体高、体斜长、胸围、腹固、管围、尻高、尻宽、腰角宽、乳房深度、后房高度、前房附着、乳头长度、乳头外径等13个体型线性性状,收集395头奶牛305 d产奶量.结果表明:前房附着,乳头外径与305 d产奶量相关极显著(P0.05);体斜长、胸围、尻宽、后房高度和前房附着对305 d产奶量的通径系数达到显著水平(P相似文献   

Associations between defensin polymorphism and somatic cell count in milk and milk utility traits in Jersey dairy cows

The aim of the study was to investigate associations between combined defensin genotypes (CDGs) and somatic cell count (SCC) in Jersey cows. The study included a herd of 184 dairy Jersey cows from Wielkopolska region in Poland. Polymerase chain reaction-restriction fragment length polymorphism analysis with TaqI restrictase established the existence of 12 CDGs with a frequency of over 1%. The most frequent were A1A2B1B2C1C2 and A1A2B1B2C1- genotypes with a frequency of 56.9783% and 12.5% respectively. The study also confirmed the existence of a statistically significant association between SCC and the year of study, season, lactation stage and cow. The highest SCC (transformed into a logarithmic scale) was found in the milk of cows with A1-B1-C1C2 genotype, whereas the lowest one in cows with A2-B1B2C1C2 genotype. Another aim of the project was to study the association between CDG and milk production traits, such as daily milk yield and fat and protein content. CDG was found to be a significant factor affecting daily milk yield and non-significant for fat and protein content. The highest daily milk yield was observed in cows with CDGs A1A2B1B2C2- and -A2-B1B2C1-, whereas the lowest one was characteristic of -A2-B1-C1C2 and A1A2B1-C1- animals. Fat content was found to be related to CDG genotype in the opposite way; the highest values were recorded in animals with -A2-B1B2C1- genotype, the lowest - in animals with -A2-B1-C1C2 genotype. Similar results were observed in protein content in milk -A2-B1B2C1-, the highest content and -A2-B1-C1C2, the lowest content. The results confirm the hypothesis of using CDG as an SCC marker. However, further studies should be conducted to confirm these results before CDG can be used as a marker in a mass selection of dairy cows.     

Segmented regression to describe cumulative milk production of grazing dual-purpose Holstein-Zebu cows

The objective of this study was to compare the fit of seven functions to cumulative daily milk yield records of grazing F1 (Holstein × Zebu) cows in a dual-purpose cattle production unit of the Mexican tropics. Fifty-seven lactations from cows that calved from 1998 to 2001 were used. The functions were quadratic without intercept, three with two segments (both segments linear, the first segment quadratic and the second linear, and both segments quadratic), and three classical growth functions (Gompertz, logistic, and Richards). The Akaike information criterion corrected (AIC_C) was used as criterion of fit, being the function with the best fit the one with the lowest AIC_C value. The best fit was for the segmented function with both segments quadratic, followed closely by the Richards function. The derivatives of these functions give the daily milk yield curve (kg/cow/day), so the former results in a straight line per segment and the latter in the usual shape of the typical lactation. However, as cumulative records produce a monotonic increasing line, neither function can distinguish a priori the presence of a lactation peak. For this reason, it is advisable to examine the common dispersion plot of daily milk yield of each cow, and if a peak is not evident, then proceed to fit the segmented function; otherwise, the function of Richards should be used. The need to study the causes for the absence of a lactation peak in tropical dual-purpose cows is highlighted.

     

Association between exposure to Neospora caninum and milk production in dairy cows

OBJECTIVE: To determine association between exposure to Neospora caninum and milk production in dairy cows. DESIGN: Prospective observational study. Animals: 565 Holstein cows. PROCEDURE: Cows were classified as seropositive or seronegative to N. caninum within 7 days after calving by use of a kinetic ELISA. Milk production was compared between seropositive and seronegative cows. RESULTS: On the basis of 305-day mature equivalent milk production data, seropositive cows produced less milk (2.8 lb/cow per day) than did seronegative cows. In addition, analysis of results throughout the first 300 days of lactation revealed that after adjusting for effects of lactation number, calving season, clinical mastitis, and lameness, milk weight of seropositive cows was 2.5 lb/cow per day less than that of seronegative cows. CONCLUSIONS AND CLINICAL RELEVANCE: Exposure to N. caninum was associated with a 3 to 4% decrease in milk production. A decrease in milk production of 800 lb/cow for a typical 305-day lactation represents a loss of $128/cow.     

西门塔尔牛CS基因多态性与肉质性状的相关性分析

以柠檬酸合成酶基因（citrate synthetase,CS）为候选基因,分析了该基因外显子3的遗传多态性与西门塔尔牛肉质性状的相关关系。选用95头西门塔尔牛为试验材料,采用PCR-RFLP的方法对该基因的外显子多态性进行检测,并利用SPSS软件对该外显子多态性与肉质性状的相关性进行分析。结果表明：CS基因第三外显子第206bp处存在G/A突变,该基因多态性与脂肪颜色呈显著相关,AA型显著高于BB型。对其他性状的影响差异不显著。通过研究CS基因外显子的多态性,为西门塔尔牛利用该基因的多态性进行分子育种提供了试验依据。     

Relationship between profitability and type traits and derivation of economic values for reproduction and survival traits in Chianina beef cows

The objectives of this study were 1) to propose a profit function for Italian Chianina beef cattle; 2) to derive economic values for some biological variables in beef cows, specifically, production expressed as the number of calves born alive per year (NACY), age at the insemination that resulted in the birth of the first calf (FI), and length of productive life (LPL); and 3) to investigate the relationship between the phenotypic profit function and type traits as early predictors of profitability in the Chianina beef cattle population. The average profit was 196 Euros/(cow.yr) for the length of productive life (LPL) and was obtained as the difference between the average income of 1,375 Euros/(cow.yr) for LPL and costs of 1,178 Euros/(cow.yr) of LPL. The mean LPL was equal to 5.97 yr, so the average total phenotypic profit per cow on a lifetime basis was 1,175 Euros. A normative approach was used to derive the economic weights for the biological variables. The most important trait was the number of calves born alive (+4.03.cow(-1).yr(-1) and +24.06 Euros/cow). An increase of 1 d in LPL was associated with an increase of +0.19 Euros/(cow.yr) and +1.65 Euros/cow on a lifetime basis. Increasing FI by 1 d decreased profit by 0.42 Euros/(cow.yr) and 2.51 Euros/cow. Phenotypic profit per cow had a heritability of 0.29. Heritabilities for eight muscularity traits ranged from 0.16 to 0.23, and for the seven body size traits between 0.21 and 0.30. The conformation trait final score can be used as an early predictor of profitability. The sale price of the animal and differences in the revenue and costs of offspring due to muscularity should be included in a future profit function.     

Lactation length in Venezuelan dual-purpose cows

Short lactations are frequently excluded from the analyses of milk records of tropical cattle. The practice leads to overestimates of milk yield and lactation length and decreases the accuracy of selection procedures. The objectives of this paper are to quantify lactation length using unselected records from a sample of Venezuelan dual-purpose cows, evaluate some of the sources of variation and discuss suitable editing procedures for milk production records in these populations.     

Relationships between lactational incidence of displaced abomasum and milk production traits in German Holstein cows

The objective of this study was to analyse the heritabilitiy of the lactational incidence of displaced abomasum (DA) and the relationships of DA with milk production traits in German Holstein cows. Data were recorded between February 1999 and January 2000 in cooperation with five veterinary practitioners. Their veterinary practices were located in the northern part of Lower Saxony. The investigation included 160 dairy farms under the official milk-recording scheme with 9,315 cows. The lactational incidence of the left abomasal displacement amounted to 1.21%, and of the right abomasal displacement to 0.41%, respectively. The linear heritability estimates for the lactational incidences of left and right DA were h(2) = 0.05 +/- 0.012 and h(2) = 0.004 +/- 0.005, respectively. Using the Dempster-Lerner-transformation the corresponding heritabilities were h(2) = 0.53 and 0.09, respectively. Milk losses for the lactation when DA was diagnosed were significant and reached 1016 kg milk, 41 kg fat, 36 kg protein and 0.07% protein. Fat content significantly increased by 0.18%. The analysis could not show significant differences between cows diagnosed with DA and cows not diagnosed with DA in the 305-day milk production traits of the lactation preceding the diagnosis of DA. There was also no indication for an unequal distribution of breeding values for milk performance traits between cows with and without DA. The additive genetic correlations between 305-day milk performance and left DA were low. The results indicated that cows with a high milk production and superior breeding values for milk performance were not exposed to an increased risk for DA.     

Association between anti-F. hepatica antibody levels in milk and production losses in dairy cows

This study was conducted to determine: (1) the associations between anti-Fasciola hepatica antibody levels in milk and some productive and reproductive parameters in dairy cattle, and (2) the threshold antibody level associated with loss of productivity, at both herd and individual level. Anti-F. hepatica antibodies were analysed by MM3-SERO ELISA in milk samples from the bulk tanks of 490 dairy farms and from 686 lactating cows. The results of general linear model analysis revealed a significant (P<0.05) negative association between the F. hepatica infection status at herd level, determined by analysis of specific antibodies in bulk tank milk, and the average herd milk production. Highly positive herds (MM3-SERO ELISA result>0.405) produced an average of 1.5 kg milk/cow per day less than the negative herds. At cow-level, the mixed model analysis also revealed a significant (P<0.05) association between anti-F. hepatica antibody levels and milk yield. A significant (P<0.05) average reduction of 2 kg milk/day was observed in cows with highly positive ELISA results (>0.762) in relation to cows with negative results. The results of the study led us to conclude that MM3-SERO ELISA is a powerful tool that can be successfully applied, if appropriate "economic thresholds" are established, to identify herds and cows suffering from milk production losses associated with natural infection by F. hepatica.     

Association analysis between variants in bovine progesterone receptor gene and superovulation traits in Chinese Holstein cows

The objective of this study was to identify a predictor to forecast superovulation response on the basis of associations between superovulation performance and gene polymorphism. The PCR-RFLP method was applied to detect two reported single nucleotide polymorphisms (SNPs) of G59752C and T81637C (rs41614030) located in introns 3 and 4 of the bovine progesterone receptor (PGR) gene in 171 Chinese Holstein cows treated for superovulation and evaluate its associations with superovulation traits. In polymorphic locus 81637, all cows without superovulation response were g.81637TC and g.81637TT genotypes. Association analysis showed that these two SNPs had significant effects on the total number of ova (TNO) (p<0.05), and the T81637C polymorphism was significantly associated with the number of transferable embryos (p<0.05). In addition, significant additive effects (p<0.05) on TNO were detected in the polymorphisms of G59752C and T81637C. These results showed for the first time that the G59752C and T81637C polymorphisms in PGR gene were associated with superovulation traits and indicated that PGR gene can be used as a predictor for superovulation in Chinese Holstein cows.     

Conversion of breeding values for milk from foreign populations

An estimate of a transmitting ability for milk in population or Country 1 (T^A₂)might be converted to an estimate for Country or Population 2 (T^A₂) by the equation proposed by the International Dairy Federation (IDF): (T^A₂)=a+b (TA₂). In this paper the derivation of the IDF equation is given and three procedures to estimate the equation parameters, a and b, are discussed as alternatives for the least-squares procedure, which yields biased and inconsistent estimates in this case. In the first procedure, parameters are estimated from a functional relationship model, where sire contributions are considered to be fixed. The second procedure is a linear regression with bias correction. In the third procedure, the parameters for the IDF equation are computed from estimates of population means and sire variances. When these population parameters are repeatedly estimated and the genetic correlation between the traits in both countries/populations is unity, the equation parameters are easily obtained by Procedure 3. When a and b have to be estimated from a sample of sires used in both countries, Procedure 1 is recommended from a mathematical viewpoint.     

Genetic and phenotypic parameters for conformation and yield traits in three Swiss dairy cattle breeds

This study presents genetic parameters for conformation traits and their genetic and phenotypic correlations with milk production traits and somatic cell score (SCS) in three Swiss dairy cattle breeds. Data on first lactations from Holstein (67 839), Brown Swiss (173 372) and Red & White breeds (53 784) were available. Analysed conformation traits were stature and heart girth (both in cm), and linear scores of body depth, rump width, dairy character or muscularity, and body condition score (only in Holstein). A sire model, with relationships among sires, was used for all breeds and traits and variance components were estimated using AS‐REML. Heritabilities for stature were high (0.6–0.8), and for the linear type traits ranged from 0.3 to 0.5, for all breeds. Genetic correlations with production traits (milk, fat and protein yield) and SCS differed between the dairy breeds. Most markedly, stronger correlations were found between SCS and some conformation traits in Brown Swiss and Red & White, indicating that a focus on a larger and more ‘dairy’ type in these breeds would lead to increased SCS. Another marked difference was that rump width correlated positively with milk yield traits in Holstein and Red & White, but negative in Brown Swiss. Results indicate that conformation traits generally can be used as predictors for various purposes in dairy cattle breeding, but may require specific adaptation for each breed.     

Association analysis between bilateral convergent strabismus with exophthalmus and milk production traits in dairy cattle

Bilateral convergent strabismus with exophthalmus (BCSE) is characterized in cattle by a symmetrical antero-medial rotation and protrusion of the eyeballs. This eye defect is caused by an inherited, centrally insufficient function of the eye muscles recti laterales and retractores. In German Brown cattle a monogenic, autosomal dominant inheritance proved to be most probable in complex segregation analysis. In our study running between October 1993 and May 1995 a total of 200 affected German Brown cows was studied. The investigation of the association between milk production traits and BCSE was based on 10,960 German Brown cows. The analysis revealed no significant differences between affected and non-affected cows, nor between cow families with and without affected members. There was no indication of an association between milk production traits and occurrence of BCSE within cow families. Linkage or pleiotropy of the BCSE locus with quantitative trait loci for milk production traits may be rather unlikely.     

Contribution of breed, cow weight, and milk yield to the traits of heifers and cows in four beef breeding systems.

Measurements were taken on 216 cows with 469 calvings for weight at weaning, condition at weaning, milk yield, milk fat percentage, milk lactose percentage, milk protein percentage, dry period feed intake, lactation period feed intake, total feed intake, first-service pregnancy rate, pregnancy rate, and days to pregnancy. Measurements were also taken on 183 heifers for first-service pregnancy rate, days to pregnancy, and age at first calving. The data spanned the years 1980 to 1988; animals belonged to one of four breeding systems: Hereford, small rotation (Angus, Gelbvieh, Pinzgauer, Tarentaise), large rotation (Charolais, Maine Anjou, Simmental), and Angus-large rotation (cows with Angus sires and large-rotation dams). Maine Anjou-sired cows had lower annual feed intake and Charolais-sired heifers lower first-service pregnancy rate than the other large-rotation breeds. Gelbvieh-sired cows had lower milk lactose and protein percentages than the other small-rotation breeds. Within breeding system neither cow weight nor milk yield were significantly associated with reproductive traits of cows. No differences among breeding systems in associations between feed intakes and weights or milk yields were detected.     

Genetic parameters for claw health and feet and leg conformation traits in Finnish Ayrshire cows

Genetic parameters for different claw disorders, overall claw health and feet and leg conformation traits were estimated for Finnish Ayrshire cows. The merged data set with records of claw health and feet and leg conformation traits consisted of 105 000 observations from 52 598 Finnish Ayrshire cows between 2000 and 2010. The binary claw health data and the linearly scored conformation data were analysed using an animal model and restricted maximum likelihood method by applying the statistical package ASReml. Binomial logistic models with mixed effects were used to estimate genetic parameters for sole haemorrhages, chronic laminitis, white‐line separation, sole ulcer, interdigital dermatitis, heel horn erosion, digital dermatitis, corkscrew claw and overall claw health. Estimated heritabilities for different claw disorders using a binomial logistic model ranged from 0.01 to 0.20. Estimated heritability for overall claw health using a binomial logistic model was 0.08. Estimated heritabilities for feet and leg conformation traits ranged from 0.07 to 0.39. The genetic correlations between claw health and feet and leg conformation traits ranged from ?0.40 to 0.42. All phenotypic correlations were close to zero. The moderate genetic correlation, together with higher heritability of feet and leg conformation traits, showed that RLSV (rear leg side view) is a useful indicator trait to be used together with claw trimming information to increase the accuracy of breeding values for claw health in genetic evaluation.     

Association between single nucleotide polymorphisms (SNPs) and milk production traits in Italian Brown cattle

Italian Brown is a cattle breed largely exploited in the production of many dairy products in Italy, including typical and traditional cheeses. For this reason, the improvement of selection methods is of economic relevance while a deeper understanding of the genetic mechanisms regulating milk production is of general scientific interest. We selected a total of 561 samples, representing virtually all Italian Brown bull population, to test for association between milk production traits and 29 known genes harbouring 106 single nucleotide polymorphisms (SNPs). After filtering, a total of 31 SNPs in 22 candidate genes and 473 bulls were retained. Associations between each SNP and milk traits were tested by a mixed model approach, obtaining seven significantly associated SNPs, two of which (in β-Lactoglobulin) associated with all traits, and four (in Chemokin receptor I, αs1 casein, k casein, fatty acid synthase, thyroid hormone responsive and Oxytocin prepropetide genes) associated with at least one trait.     

Blood biochemical values in Japanese Black breeding cows in Kagoshima Prefecture,Japan

To obtain blood biochemical basic data of Japanese Black breeding cows in Kagoshima Prefecture, Japan, blood samples were obtained from 857 clinically healthy multiparous cows on 71 farms. Cows were divided into three stages: the prepartum stage (between 20 and 80 days before parturition, n=290), lactation stage (between 20 and 80 days after parturition, n=283) and maintenance stage (between 120 and 200 days after parturition, n=284). The mean concentration of total protein and total cholesterol, and the mean activities of aspartate aminotransferase in the lactation stage tended to be higher than those in the prepartum and maintenance stages. The mean concentration of glucose in the prepartum stage tended to be lower than that in the lactation and the maintenance stages. The mean concentration of nonesterified fatty acids and beta-hydroxybutyrate in the prepartum stage tended to be higher than those in the lactation and maintenance stages. The mean concentration of serum retinol was approximately 30 µg/dl in all stages. These results suggest that the blood biochemical values of multiparous Japanese Black cows vary with breeding stages, and it is considered that the blood parameters obtained in this study are useful as indices for health management of Japanese Black breeding cows.