Published online by Cambridge University Press: 02 September 2010
A study was made to investigate the influence of pregnancy feeding level (ad libitum (AL) and restricted (R); 2·0 kg food per day) and lactation length on growth, carcass, meat quality and processing characteristics of pregnant gilts (P) slaughtered after weaning on day 0 (P·0), day 10 (P·10) or day 35 (P·35) after farrowing. Non-pregnant (NP) control gilts were slaughtered at live weights of approximately 95 kg (NP-L), 135 kg (NP-M), and 160 kg (NP-H). P gilts were mated at an average age of 172 days and an average live weight of 97 kg. Pregnancy per se reduced live weight and lean growth rates compared with NP-H animals which were slaughtered at a similar age to the once-bred animals. Weight loss during lactation tended to increase with lactation length and was higher for gilts given food ad libitum during pregnancy compared with restricted animals. The weight of closely trimmed lean in the carcass was similar for the P·0, P·10 and P·35 groups (59·5 v. 62·2 v. 58·8 kg respectively; average s.e. 2·42) and all once-bred gilt groups virtually doubled trimmed lean yields during pregnancy and lactation. Curing yields were similar for P and NP gilts. As lactation length increased, the fat content of the longissimus dorsi and of the overlying subcutaneous fat layers tended to decrease and the moisture content of these two tissues increased. The major impact offeeding level was on fat levels which were significantly higher for AL animals. Trimmed lean yields were also higher for AL gilts suggesting that lean growth rates were not being maximized on the R feeding regime. Subjective muscle colour scores indicated that the longissmus dorsi from P gilts was darker than from NP-L animals and muscle colour tended to become darker with increasing lactation length. There were few significant differences between treatment groups for eating quality. Meat from once-bred gilts was generally judged to be tougher than that from NP-L animals and toughness generally increased with lactation length. This study confirms the potential of the once-bred gilt as an efficient producer of pig meat but raises issues regarding meat quality that require further research.