Effect of inter-breed embryo transfer on lamb growing performance and survival

The roles of recipient and embryo genotype in determining the growth performance and survivability of offspring based on specific behavioural differences were investigated using inter-breed embryo transfer. This study was carried out using three recipient genotypes (Awassi, Redkaraman and Tuj) and two embryo genotypes (Charollais and Romanov) to obtain the six possible combinations of ewe and lamb genotypes. Data were collected from 71 recipient ewes (10 Redkaraman with Charollais and 15 Redkaraman with Romanov embryos; 10 Tuj with Charollais and 12 Tuj with Romanov embryos, and 12 Awassi with Charollais lambs and 12 Awassi with Romanov embryos); all ewes received two frozen-thawed embryos. Awassi ewes had a significantly longer duration of the licking/grooming event (25.5min, p<0.05) than Tuj ewes. Charollais lambs were significantly (p<0.05) more likely to require birth assistance compared to Romanov lambs. Romanov lambs were significantly more (p<0.01) active than Charollais lambs in the first 2h after birth; ewe breed had no effect on lamb behaviour. There was no recipient breed effect on either birth or weaning weights of lambs. Charollais lambs were recorded with higher birth (5.5±0.3kg vs 3.9±0.2kg; p<0.001) and weaning (29.4±1.2kg vs 22.4±1.9kg; p<0.001) weights compared to Romanov lambs. At weaning Romanov lambs had significantly higher (95% vs 75%; p<0.05) survival rates, however, this was not significantly affected by recipient breed. It was concluded that recipient breed was not an important factor in survival and weaning performance of embryo transferred lambs from a prolific breed (Romanov) while these traits recorded for lambs from meat type (Charollais) embryos were influenced by dam breed.