ABSTRACT:The relationships between conformation traits and longevity traits were analyzed in 41 489 Holstein cows born in the years 1994-1999 which were culled by 30 th June 2005. Pearson correlation coefficients between type traits and the herd life or productive life of cows were calculated. The effects of type trait scoring level on the length of productive life were described by means of analyses of variance. The observed correlations between herd life or productive life and type traits are in the range of -0.061 to 0.160. Negative correlations were found for rump angle, rear leg set, udder depth, and teat length. Most of the body traits had slightly positive relationships to herd life, indicating that larger cows live longer. However, body depth and chest width did not have a linear relation to longevity traits. The longest productive life was found in cows undersized in chest width and body depth (P < 0.01). A similar dependence was also found for rump width (P < 0.01). The ideal rear leg set for longevity was scored as average or below average, i.e. moderately curved or slightly straight legs (P < 0.05). Cows with well-attached fore udder, high attached rear udder, strong central ligament, close front teat placement, and with moderately long teats showed the longest functional productive life (P < 0.05-0.001). Linear relationships between longevity traits and general conformation characteristics were found as well.

The objective of this study was to evaluate the effect of body condition score (BCS), body weight (BW), average daily weight gain (ADG), and age at first calving (AFC) of Holstein heifers on production and reproduction parameters in the 3 subsequent lactations. The data set consisted of 780 Holstein heifers calved at 2 dairy farms in the Czech Republic from 2007 to 2011. Their BW and BCS were measured at monthly intervals during the rearing period (5 to 18 mo of age), and the milk production and reproduction data of the first 3 lactations were collected over an 8-yr period (2005 to 2012). The highest milk yield in the first lactation was found in the group with medium ADG (5 to 14 mo of age; 0.949 to 0.850 kg of ADG). The highest average milk yield over lifetime performance was detected in heifers with the highest total ADG (≥ 0.950 kg/d). The difference in milk yield between the evaluated groups of highest ADG (in total and postpubertal growth ≥ 0.950 kg/d and in prepubertal growth ≥ 0.970 kg/d) and the lowest ADG (≤ 0.849 kg/d) was approximately 1,000 kg/305 d per cow. The highest milk yield in the first lactation was found in the group with the highest AFC ≥ 751 d, for which fat and protein content in the milk was not reduced. Postpubertal growth (11 to 14 mo of age) had the greatest effect on AFC. The group with lowest AFC ≤ 699 d showed a negative effect on milk yield but only in the first 100 d of the first parity. The highest ADG was detrimental to reproduction parameters in the first lactation. The highest BW at 14 mo (≥ 420 kg) led to lower AFC. Groups according to BCS at 14 mo showed no differences in AFC or milk yield in the first lactation or lifetime average production per lactation. We concluded that low AFC ≤ 699 d did not show a negative effect on subsequent production and reproduction parameters. Therefore, a shorter rearing period is recommended for dairy herds with suitable management.

Genetic and phenotypic correlations between production traits, selected linear type traits, and somatic cell score were estimated. The results could be useful for breeding programs involving Czech Holstein dairy cows or other populations. A series of bivariate analyses was applied whereby (co)variance components were estimated using average information (AI-REML) implemented via the DMU statistical package. Chosen phenotypic data included average somatic cell score per a 305-day standard first lactation as well as the production traits milk yield, fat yield, protein yield, fat percentage, and protein percentage per the standard first lactation. Fifteen classified linear type traits were added, as they were measured at first lactation in the Czech Holstein population. All phenotypic data were collected within the progeny testing program of the CzechMoravian Breeders Corporation from 2005 to 2009. The number of animals for each linear type trait was 59 454, except for locomotion, for which 53 424 animals were recorded. The numbers of animals with records of milk production data were 43 992 for milk yield, fat percentage, protein percentage, and fat-to-protein percentage ratio and 43 978 for fat yield and protein yield. In total, 27 098 somatic cell score records were available. The strongest positive genetic correlation between production traits and linear type traits was estimated between udder width and fat yield (0.51 ± 0.04), while the strongest negative correlation estimated was between body condition score and fat yield (−0.45 ± 0.03). Other estimated correlations were between those two extremes but generally they were close to zero or positive. The strongest negative phenotypic correlations were estimated between udder depth and milk yield and protein yield (both −0.17), while the strongest positive phenotypic correlations were estimated between milk yield, protein yield, and udder width (both 0.32).

Test-day records of somatic cell count (SCC), milk yield, fat and protein content and six linearly scored type traits (fore udder attachment, udder depth, central ligament, rear udder height, front teat placement, teat length) of 22 613 first lactation cows from 117 herds were included in this study. SCC was log-transformed into somatic cell score (SCS). Milk yield was standardized as follows: MILK = milk yield (fat content + protein content)/(3.8 + 3.2). For each analyzed type trait, cows were assigned to one of the three levels according to linear type score: level 1 (score 1 and 2); level 2 (score 5 and 6); level 3 (score 8 and 9). A linear model was used to estimate the effect of different type traits on MILK and SCS. The highest values of SCS were found for the first levels. The differences between the first and second level were on average 0.33, 0.54, 0.28, and 0.36 for fore udder attachment, udder depth, central ligament and rear udder height, respectively. The cows with deep udders, weak central ligaments and fore attachments and low rear udder height showed the highest SCS. Low SCS appeared to be associated with an intermediate distance between the front teats and longer teats. The third level of udder depth (shallow udder) had low MILK. Rear udder height showed low MILK for the first level (low height) with the highest MILK values for the third level (high height). The average difference was 3.3 kg.

ABSTRACT:The impact of polymorphism of the diacylglycerol acyltransferase (DGAT1), butyrophilin (BTN1A1), oxidized low-density lipoprotein receptor (OLR1), and signal transducer and activator of transcription 1 (STAT1) genes on milk production and reproduction traits in 419 Czech Fleckvieh cows was examined using polymerase chain reaction and restriction fragment length polymorphism. The loci DGAT1 and BTN1A1 were observed simultaneously to affect milk production, estimated breeding value of milk production traits, as well as reproduction parameters. Significant differences were found also between genotypes of the STAT1 loci in relation to estimated breeding value of milk production traits. Similar findings in pure dairy breeds suggest that heterogeneous effects of the observed loci can be explained by different genetic backgrounds in various breed populations selected to achieve different commercial goals. Thus, it is necessary to determine variability and influence of a molecular marker in a specific population when considering its inclusion into a breeding programme.