The aim of this study was to assess the influence of genotypes from the CSN3 and LGB loci on milk production and chemical composition in Romanian Simmental cattle (n=114). For the CSN3 locus a significantly higher frequency (P≤0.001) was observed for the allele A (0.785) compared to allele B (0.215) and for AA (0.631) compared to AB (0.307) and BB (0.062) genotypes, respectively. The AA genotype was associated with a higher milk production (5887.76±115.7 kg) compared to the yields associated with the BB genotype (5619±86.34 kg, P≤0.003), as well as a higher fat percentage (4.19±0.05% vs. 4.01±0.02%, P≤0.001). A higher milk protein percentage was associated with BB (3.4±0.02%) compared to AA (3.27±0.03) and AB (3.29±0.03) genotypes, respectively (P≤0.05). For the LGB locus, the frequency of allele A was significantly higher (0.606, P≤0.008) than allele B (0.394). The AB genotype was the most prevalent in the herd (0.579) compared to AA (0.316) and BB genotypes (0.105). The AB genotype was associated with a higher milk production (5906.54±166.76 kg) compared with the other two genotypes (P≤0.05). The BB genotype was associated with a higher fat percentage in milk (4.23±0.06%) compared with AA (4.17±0.06) and AB (4.2±0.08) genotypes, respectively (P≤0.01). For the LGB locus, no significant differences (P>0.05) were observed for milk protein percentage. In order to increase the quantity and quality of milk, the outcomes obtained in this study encourage improving genetic structure in cattle based on marker assisted selection for genes with economic values.

No abstract

The aim of this study was to measure the effect of season and climate variations on thermal comfort and behaviour of 6-month-old dairy calves housed in a semi-opened shelter to develop animal-based indicators for assessing animal thermal comfort. The ultimate purpose was to further exploit the use of those indicators to prevent thermal stress by providing appropriate care to the animals. Measurements were taken for winter and summer seasons. Results showed that season significantly influenced (P ≤ 0.01) the lying down behaviour of calves by reducing the time spent lying, from 679.9 min in winter to 554.1 min in summer. Moreover, season had a significant influence (P ≤ 0.01) on feeding behaviour. In detail, the total length of feeding periods was shorter in winter, 442.1 min in comparison to 543.5 min in summer. Time spent drinking increased significantly (P ≤ 0.001), from 11.9 min in winter to 26.9 min in summer. Furthermore, season had a significant influence (P ≤ 0.001) on self grooming behaviour which was 5.5 times longer in duration in winter than in summer (1,336 s vs 244 s). It was concluded that calves' thermal comfort is affected by seasonal and climate variations and that this can be assessed by measuring behaviour with animal-based indicators, such as lying down, resting, standing up, feeding, rumination, drinking and self grooming. The indicators developed may be a useful tool to prevent animal thermal stress by providing appropriate housing and handling to calves under seasonal and climate challenge.