Induced out of season reproduction in hoggets of the Austral breed

Abstract

The effects of out of season oestrus-ovulation induction treatment were studied in eighty four fourteen month old Austral breed hoggets, weighing 39.4 ± 3.4 kg, through their reproductive and productive response and the natural reproductive activity during November (Spring). 
Initially, the animals were randomly allocated into 2 groups of 42 each. Group 1 was treated for 12 days with a 0.3 g progesterone intravaginal device and at the moment of withdrawal, injected with 250 IU of PMSG. Nine out of 42 (21.4%) devices were lost and those animals were discarded. Group 2 acted as control. 
The hoggets were managed as a single group and paddock mated with 3 Austral harnessed rams for 34 days. 96.9% (32/33) of the treated hoggets in Group 1 showed oestrus and were mounted. 7.1% (3/42) in Group 2 were mounted. 75.7% of the hoggets in Group 1 lambed (25/33) over 7 days, producing 42 lambs (159.3%). Hoggets in Group 2 did not lamb. 
The treatment employed is a good oestrus-ovulation inductor in the deep anoestrus season; the differences between groups being highly significant (p ­ 0.01). Loss of vaginal devices was exceptionally high. Austral hoggets in the conditions of this experiment did not show relevant sexual activity in November. No significant differences in liveweights or body condition were detected in hoggets which lambed 0, 1 or 2 lambs.