Influence of age at weaning and kind and protein content of starter on rate and efficiency of gain of growing swine, and carcass characteristics.

I T is sometimes implied that pigs weaned at 14 to 21 days of age must be fed very acceptable and highly nutritious pig starters to prevent stunting or a "check" (Smith and Lucas, 1956) following early weaning, and to assure maximum and most efficient gains during the growing period subsequent to 56 to 63 days of age. Hanson, Rut]edge and Ferrin (1954) and Hanson et al. (1955) reported that pigs weaned at 3 wk. tended to gain less rapidly and efficiently subsequent to 8 wk. than pigs weaned at 8 weeks. Subsequently, Hanson (1956) demonstrated that inclusion of dried whey, dried condensed fish solubles or a fermentation product in the pig starter, or feeding a high sugar starter, did not favorably influence rate and efficiency of gain beyond 8 wk. of age. Several investigators (Lucas, Calder and Smith, 1959; Blair, 1961; Boaz and Elsley, 1962; Elsley, 1963; Nielsen, 1964; Duckworth, 1965) have been unable to demonstrate that heavy 56-day weights of pigs weaned at an early age, or nursing their dams to 56 days, resulted in more rapid and efficient gains during the subsequent growing period, or in leaner carcasses. The objectives of these experiments were to determine the effects of age at weaning, protein content of starter fed to pigs weaned at 3 wk. and kind of starter on rate and efficiency of gain of pigs to 8 wk., or about 20 kg., and on rate and efficiency of gain during the final growing period, carcass characteristics and composition of the lean tissue.