Effect of varying ideal protein level on the performance of growing-finishing swine.
1989
Haydon K.D. | Harrison M.D. | Dove C.R.
Ninety-six crossbred pigs (18.1 kg, initially) were used to evaluate six levels of ideal protein on growing-finishing perforance (8 castrates and 8 females/diet). Experimental diets were fortified corn-soybean meal based, formulated to contain approximately 15.0 and 13.0% crude protein for grower and finishing periods, respectively. Ideal protein levels (IP) were varied by the addition of L-lysine-HCl, L-tryptophan, L-threonine or DL-methionine on a similar nitrogen basis. Calculated ideal protein percentage of crude protein ranged from 66 to 95% in the grower phase (18 to 50 kg) and 64 to 100% in the finisher phase (50 to 105 kg). Increasing IP levels resulted in linear (P less than .10) and quadratic (P less than .10) improvements in daily gains of growing barrows and gilts, respectively. Daily feed intake of growing gilts was linearly (P less than .01) decreased with increasing IP level resulting in a linear (P less than .01) improvement in feed utilization. No differences (P greater than .20) were observed for live weight gain in the finisher phase or measured over the entire study for either sex. Feed intake of gilts in the finishing phase was not influenced by IP level. However, feed intake of castrates responded quadratically (P less than .10) with increasing dietary IP level. Gain:feed ratios for gilts were linearly (P less than .10) improved with increasing IP level in finisher phase and over the entire study. Data indicate the growing pig will respond to higher dietary IP levels, however, protein does not appear as a limiting factor for finishing performance.
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