Effect of birth year on the weight development of male lambs of the Middlerodopean sheep breed
DOI:
https://doi.org/10.61308/KMQA3931Keywords:
sheep, Middlerodopean sheep breed, live weight, average daily gain, birth year effectAbstract
The aim of the study was to determine the effect of birth year on the weight development of weaned male lambs of the Middle-Rhodope sheep breed. The study included 296 weaned male lambs (88 at 100 days of age, 104 at 180 days of age and 104 at 270 days of age), reared at a ram-breeding farm of the ARSRKCRZO Association – Smolyan, owned by a farmer in the village of Zagorsko, Momchilgrad Municipality, Kardzhali Province. The study was conducted over five consecutive years (2020 - 2024). Lambs were fed according to established norms with free access to water, and reared under a semi-intensive system. Individual live weights were measured with a calibrated electronic scale with an accuracy of 0.1 kg, in the morning on an empty stomach. Average daily gain was calculated for each study period per year. Data were processed using the methods of variation statistics. The effect of birth year was determined using the one-way analysis of variance (ANOVA) model. The significance of the factor effect was assessed by Fisher's F-criterion, and the significance of differences between study groups by Student's t-test, using the Data Analysis statistical package, Excel 2021, Microsoft. A highly significant effect of birth year (P<0.001) was established at all ages studied, with the strongest effect at 100 days of age, where 38.1% of the observed variation in live weight was attributable to birth year. At 270 days of age, lambs born in 2022 achieved the significantly highest live weight (47.26 kg), whilst those born in 2021 had the significantly lowest (36.60 kg). Average daily gain varied considerably across years and periods. Male lambs born in 2020 exhibited marked compensatory growth over the 100 - 270-day period of 137.3 g/day, which was significantly higher (P<0.001) than in all other years studied.
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