Plane of nutrition during the rearing phase for replacement ewes of four genotypes: II - effects on performance during first pregnancy and to weaning, and of their progeny

• Published in: Animal (Cambridge, England) England), 2018-04, Vol.12 (4), p.722-732
• Main Authors: Keady, T. W. J., Hanrahan, J. P.
• Format: Article
• Language: English
• Subjects: Animal lactation; Animals; Birth; Cattle; Childbirth & labor; Dry matter; Factorial design; Feeds; Genotype & phenotype; Genotypes; Grasslands; herbage allowance; Lamb; lamb growth; litter size; Mutation; Nutrition; Offspring; Ovis aries; Ovulation; Pregnancy; Progeny; Research Article; Sheep; silage feed value; Summer; sward height; Weaning; Winter
• ISSN: 1751-7311; 1751-732X
• DOI: 10.1017/S175173111700204X

Plane of nutrition (PN) offered to ewe replacements during the rearing phase (8 to 17 months) and first pregnancy may affect reproductive and progeny performance when replacements are joined at ~19 months. The effects of PN offered to spring-born ewe replacements during their first winter (winter_1), second summer (summer_2) and subsequent winter (mid and late pregnancy; winter_2) were evaluated, over 3 consecutive years, using 287 ewe lambs of four genotypes: Charmoise×Scottish Blackface (C×SBF), Belclare×SBF (Bel×SBF), Belclare (Bel) and Belclare×SBF (heterozygous for a gene, either FecGH or FecXG mutations, that increases ovulation rate: BelMG×SBF). Ewe lambs were offered, daily, a deferred-grazed herbage allowance (HA) of either 0.75 or 1.75 kg dry matter during winter_1. During summer_2 the replacements were set-stocked to maintain sward heights of 4 or 6 cm. Ewes were housed during mid and late pregnancy (winter_2) and offered either medium or high-feed-value grass silage, thus yielding a 2×2×2 factorial design. Increasing HA during winter_1 and residual sward height during summer_2 increased ewe BW post joining (P