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Effect of body condition on reproductive capabilities of Blonde d´Aquitaine cows
Kopečková, Tereza ; Stádník, Luděk (advisor) ; František, František (referee)
The purpose of this thesis was to determine the influence and mutual relation between the body condition of cow and the weight of calfs at birth, at 120 and 210 days of age. Next, the influence of the breeding cows body condition on the conception rate was examined. As hypothesis served the assumption that cows with optimal body condition (assesed via the BCS systém, levels 5 and 6) would have the highest conception rate and that their calfs would achieve the expected level of results at the inspection weighting. By contrast, at cows classified by the BCS system as a lower levels e.g. 4 or higher levels e.g. 7 and higher, the conception rate would decrease and the calfs would achieve worse levels at the inspection weighting.
For the evaluation, 81 cows with their calves were observed. The beginning of evaluation of the mothers condition began always approximately a week after the calving and further evaluations continued in monthly intervals. In total, six body condition assessments were made with every specimen. For the processing of data, the SAS 9.3 programme was used, namely MEANS, UNIVARIATE, CORR, REG and MIXED procedures.
The influence of BCS levels on the weight of calves at birth, at 120 and 210 days of age was not statistically significant (P > 0,05). But if we compare the occuring BCS levels in this work with the stated required range (BCS 5 to 7), the conclusion can be made that the results confirm the hypothesis. Also, a positive correlation occured between the occuring BCS level in the second assesment (P < 0,05) and the weight of calves at 120 days of age, as well as in levels of BCS in first (P < 0,01), second (P < 0,001), third (P < 0,05) assesment and the weight of the calves at 210 days of age.
The influence of individual BCS levels on the conception rate was also studied. Here, the influence was also not statistically confirmed (P > 0,05), but the comparison between the occurring BCS levels and the stated optimal range (BCS 5 to 7), the conclusion that the results confirm the hypothesis can be stated.
The order of cows calving has statistically important influence on the weight of the calves at birth, at 120 and 210 days of age. The best results were achieved by dams on the 6th and subsequent calving (P < 0,01 and P < 0,05). A positive correlation on the level of importance P = 0,05 was detected, between the order of the calving and pregnancy, but the statistically important influence was not confirmed (P > 0,05).
The influence of the calving month on the weight of the calves was confirmed only at weights at 210 days of age. The highest values were achieved by calves born in April (P < 0,01).
The influence of sex on the weight of the calves at birth, at 120 and 210 days of age was also studied. Higher values were achieved by bulls (P < 0,05).
The weight of the calves at birth affects the calving difficulty. Mothers with calves of lesser weight had demonstrably easier calving (P < 0,01). In the case of difficult calvings, the influence of calves weight on calving was not proven (P > 0,05).
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