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Effect of system of lamb rearing and season on early post‐partum fertility of ewes and growth performance of lambs in Katahdin sheep
Author(s) -
RastleSimpson S.,
D'Souza K.,
Redhead A.,
SinghKnights D.,
Baptiste Q.,
Knights M.
Publication year - 2017
Publication title -
journal of animal physiology and animal nutrition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 56
eISSN - 1439-0396
pISSN - 0931-2439
DOI - 10.1111/jpn.12551
Subject(s) - domestic sheep reproduction , zoology , biology , hay , forage , pasture , post partum , estrous cycle , seasonal breeder , fertility , agronomy , pregnancy , population , medicine , ecology , environmental health , genetics
Summary The effect of season (S), lamb rearing system ( RT ) and grain supplementation ( GS ) on post‐partum fertility in Katahdin ewes and growth in Katahdin lambs was evaluated. Katahdin ewes were bred to lamb in fall ( n = 36) or spring ( n = 56) and at approximately 2.5 months post‐partum were randomly assigned to be permanently separated or to continue to suckle their lambs for an additional 3 months. All ewes were joined with rams following treatment to synchronize oestrus. Weaned (W, n = 84) and continuously suckled lambs ( CSK , n = 88) were fed forage only ( n = 84; hay and pasture for fall‐ and spring‐born lambs respectively) or were supplemented ( n = 88; 18% crude protein ration ad libitum ) and all weighed biweekly. Ewes rebred in the fall had a shorter ram introduction to lambing interval (p < 0.05), higher prolificacy (p = 0.001) and higher lambing rates (p = 0.02); however, the proportion of ewes lambing was not affected by season. The first service lambing rate was lower in ewes continuously suckling lambs in the spring, but not in the fall breeding season (S × RT , p = 0.03). Lambs that continuously suckled their dams and were supplemented grew quicker and gained more (p < 0.001) than their weaned and unsupplemented counterparts. The effect of CSK on growth rate of lambs was greater in the spring ( RT × S; p = 0.05), and the effect of supplementation on growth rate of lambs was greater in the fall ( GS × S; p < 0.0001). In conclusion, Katahdin lambs achieved higher weight gains from continuous suckling and grain supplementation. Moreover, Katahdin ewes are capable of early rebreeding post‐partum while suckling their lambs, which makes them suited for use in accelerated lambing programmes.