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.
Highlights
Local sheep breeds are capable of sustaining extensive farming conditions [1,2]
This may encourage breeders to develop this branch of livestock production avoiding the high expenses of construction of massive, warm barns
Sheep kept in a cold environment were characterized by a lower number of corpora lutea in comparison to those staying in the warm barn (p ≤ 0.05)
Summary
Local sheep breeds are capable of sustaining extensive farming conditions [1,2]. In Poland, one of these breeds is the Żelaźnieńska sheep, a cross of local Łowicz ewes with Leicester and Polish Merino rams. Since 1955, it has been selected for reproductive performance. The body weights of ewes and rams are 65 and 95 kg, respectively. Female and males reach sexual maturity at the age of 7 months. The average age at first parturition is 24 months. The average lifetime fecundity expressed as the number of lambs weaned per ewe per year reaches 1.5 [3,4]
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