The Ovulation Rate, Plasma Leptin Concentration, and Litter Size of a Local Ewe Breed Kept in a Barn Versus Those Kept under an Overhead Shelter

Abstract

The effect of housing system on ovulation rate, leptin concentration, body weight, condition score and litter size of Żelażnieńska ewes was investigated. The observations were carried out during three successive years on 36 ewes between 2 and 4 years of age. The animals were divided into groups: the experimental group kept in a cold environment under an overhead shelter, and the control group kept in a warm barn. In both groups were ewes with similar age and reproductive performance nearing that of the flock. The average litter size was 1.53 and 1.59, respectively. This difference was not significant. The observation was carried out on the same ewes each year; thus, ewe age varied from 2 to 6 years. The ovulation rate was tasted by laparoscopy (L) on 16 September and 5 October. Blood was taken from each ewe after feeding one day before laparoscopy. The lower number of corpus lutea (p ≤ 0.01) and leptin concentration (p ≤ 0.01) at first L compared with second L was confirmed. The highest litter size (1.8) was shown by ewes at the age of 4 years (p ≤ 0.01). The Pearson correlation of ewe age and plasma leptin concentration was noted (p ≤ 0.05). The Spearman correlation of the condition score with ewe body weight (p ≤ 0.01) and with ewe age (p ≤ 0.05) was confirmed. Żelaźnieńska sheep may be housed in semiopen sheds with no negative impact on their reproduction. This may encourage breeders to develop this branch of livestock production avoiding the high expenses of construction of massive, warm barns.