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Abstract

The body condition scoring system (BCS) is a means of accurately determining body condition of dairy cows, independent of body weight and farm size. The body condition scores represent a subjective visual or tactile (or both) evaluation of the amount of subcutaneous fat in a cow. The system is a useful method of evaluating body energy reserves and is used widely for evaluating nutritional status in dairy cows. The different stages of lactation have different recommended scores. BCS change during the lactation period depends on the milk production, reproduction and health status. Extreme body condition loss in the early lactation can cause irregular heats, longer time to first ovulation, and fail to conceive. The aim of this research was to determine the effect of BCS on Holstein cows’ reproduction. The relationship between some BCS parameters: BCS at calving (BCSc), minimum BCS after calving (BCSmin) and the reduction of BCS after calving (BCSr) on one hand and three reproductive parameters: the days from calving to first service (DFS), number of inseminations to conception (NIC), and days open (DO) on the other hand were studied in three private dairy farms in South Hungary. BCS were determined monthly during milk recording. A total of 786 records of Holstein cows from 1 to 3 lactation were evaluated. DFS was significantly (P<5%) influenced by BCSs and BCSmin. The number of inseminations to conception (NIC) varied according to the individual cow. In the present study was between 1 and 12. The most favourable DO values were observed in the group having >3.5 BCSc (150.04 days), the group with 3.0-3.5 BCSmin (138.92) and the group having >1 BCSr. There was no significant relationship found between DO and the BCS groups.

Abstract

Cases of mastitis (CM) from 38,236 lactations belonging to 16,497 cows were recorded on seven farms in the Czech Republic from 1996 to 2014. Clinical mastitis was analyzed with linear animal model as an all-or-none trait for each recorded lactation (CM305) and separately for each trimester of lactation (CM1, CM2, and CM3). Bivariate linear animal models were used to estimate the genetic correlation between these CM traits and lactation means for somatic cell score (SCS305), the interval between calving and first insemination (INT) and days open (DO). Factors included in the linear model were parity, herd, year of calving, calving season, fixed linear and quadratic regression on age at first calving, fixed linear and quadratic regression on milk production in the corresponding parity, permanent environmental effect of the cow, and additive genetic effect of the cow. Estimated heritabilities of the CM traits ranged from 0.01 to 0.03. Permanent environmental effects accounted for approximately two-thirds of the phenotypic variance. Genetic correlations of SCS305 with CM traits were 0.85±0.029, 0.81±0.086, 0.82±0.087, and 0.67±0.088 for CM305, CM1, CM2, and CM3, respectively. Genetic correlations of INT with CM305, CM1, CM2, and CM3, respectively, were 0.22±0.065, 0.19±0.084, 0.20±0.121 and 0.15±0.121: and genetic correlations of DO and the four CM traits were 0.28±0.079, 0.26±0.101, 0.43±0.134, and 0.15±0.131. For the 140 sires in the dataset, Spearman rank correlations among breeding values for the four CM traits and for SCS305 were uniformly high at 0.99±0.001.