Twenty-five Californian does were mated and given pelleted diets of either 8(LE) or 10(HE) MJ/kg dry matter (ruminant metabolizable energy values) throughout gestation and lactation. Litter sizes were adjusted to six offspring per doe. Milk yield was estimated from the weight differences of the litters before and after suckling, when the opportunity for nursing was confined to once daily. The young rabbits were allowed access to either the LE or HE diets from 18 days of age. Weaning took place at 32 days of age when four rabbits from each doe grouP × pre-weaning diet were slaughtered. Diet had no effect on litter size or birth weight, but does on the LE diet had lower live weights post partum (P < 0·05). Dry-matter consumption by the does on the LE diet was greater than for the HE diet (P < 0·05) both during gestation and lactation, but calculated metabolizable energy intakes were lower during lactation. There were no statistically significant differences between treatments for milk yield or live-weight gain to weaning and dry-matter intakes of the young at weaning, but daily live-weight gain from fostering to 18 days of age was greater for litters of does fed the HE rather than the LE diet (P < 0·05). There were no statistically significant differences between diets for carcass traits at weaning.After weaning, 32 rabbits were given either the LE or HE diet until 2 kg live weight when they were slaughtered. A post-weaning × pre-weaning diet interaction (P < 0·05) occurred for live weights of the rabbits at the start of the post-weaning trial (i.e. after a 10-day adaptation period) with LE: LE rabbits being lighter than other rabbits as a results of poor live-weight gains during the adaptation period. Live-weight gains to slaughter were greater for the pre-weaning LE diet (P < 0·05) and the post-weaning HE diet (P < 0·01), although dry-matter intakes of the HE diet were less (P < 0·05). Rabbits on the LE diet had greater empty gut weights (P < 0·05) and lighter livers (P < 0·05) at slaughter.

No abstract

1983). The effect of slaughter weight upon the growth and carcass characteristics of rabbits fed diets of different dietary metabolizable energy concentrations. ABSTRACT Eighteen male and 18 female weaned rabbits were randomly allocated to two diets formulated to give energy concentrations of 8 (LE) and 10 (HE) MJ metabolizable energy per kg dry matter and three target slaughter weights (1-5, 2-25 and 3-0 kg live weight) to give a 2 x 2 x 3 factorial design with three replicates. Voluntary food intake and live-weight gain were monitored and the carcasses chemically analysed. The metabolizable energy concentrations of the diets were determined by balance and found to be 9-87 and 6-84 MJ/kg dry matter for diets HE and LE respectively.Rabbits fed the LE diet consumed more dry matter (P < 0-001) and metabolizable energy (P < 0-01) in total, but grew more slowly than those fed the HE diet (P < 0-001). A diet x slaughter weight interaction occurred (P < 0-01); rabbits of the LE-3 kg treatment took longer to reach target weight as a result of a flattening of their growth curve.Rabbits fed the LE diet had lower killing-out proportions (P < 0-05), heavier gut weights (P < 0-05) and gut contents (P < 0-05), but lighter livers than those fed the HE diet. Killing-out proportion progressively increased with increasing slaughter weight. External offal weight as a proportion of live weight tended to increase while internal offal weight as a proportion of live weight tended to decrease as slaughter weight increased. The carcasses of rabbits slaughtered at 3 kg had lower moisture contents (P < 0001), greater fat contents (P < 0001) and lower ash contents (P < 005) than other slaughter treatments. A significant diet x slaughter weight interaction occurred in fat content, with rabbits of the LE-3 kg treatment having proportionally more fat. With age at slaughter as a covariate, rabbits fed the HE diet had proportionally more fat (P < 0-05).