Progress 11/01/02 to 09/30/07
Outputs
A two year factorial study was conducted to evaluate the effects of diet type (low protein diets supplemented with crystalline amino acids vs. normal type diets) and season/rearing environment (hot humid summer vs. thermoneutral fall) on growth performance and carcass lean content of finishing pigs (52 to 110 kg). For each year, two trials, each with 84 crossbred pigs, were conducted; one during the summer and the other during the fall. The trials were conducted in north central Florida (29.5 degrees N lat.). Daily average temperatures range from a low of 22 C to a high of 32 C for summer, and 11 and 23 C for fall; rainfall averages 123 cm/yr. Diets were corn and soybean meal based (3.3 mcal ME/kg). The low protein (LP) diets were four percentage units lower in crude protein than the corresponding normal (control) diets; crystalline lysine, threonine, tryptophan and methionine were added to the LP diets to meet the pigs requirements. For each trial, two diets were used
(finisher I, from 52 to 82 kg and finisher II, 82 to 110 kg) and formulated using NRC (1998) recommendations for high lean gain potential pigs. Gilts and barrows were housed and fed separate diets. Seven pigs were allotted to each pen and the two diet types were each fed to six pens (3B, 3G) for each trial. Pigs were housed in an open sided building in pens with slotted concrete floors. Water sprinklers were used during warm weather (>25 C) over the rear half of each pen. Floor space was 0.7m2 per pig. Feed and water were offered ad libutim. Pigs reared during the summer grew, on average, 9% slower (0.88 kg/d vs 0.97, SE = 0.008; P<0.001) than pigs reared during the fall; ADF and G/F was also affected by season (P<0.001). Pigs fed the LP + aa diets averaged 3% lower (P<0.01) ADG than pigs fed the control diets; ADF and G/F were not affected (P>0.10). The decrease in ADG was most pronounced during the summer vs. fall (6% vs. 1%; SxD, P = 0.06). The decrease noted occurred only during
the finisher II phase (82 to 110 kg; 0.91 kg/d vs. 0.84); diet type had no effect on ADG during finisher I (0.97 vs 0.98 kg/d). Carcass lean content was not affected (P>0.10) by diet or season (mean = 51% fat free). The feeding of a LP amino acid supplemented diet type used in this study appears not to be of particular benefit on improving finishing pig growth performance under hot and humid conditions.
Impacts
Results could be helpful in finding dietary strategies to help minimize the negative effects of heat stress.
Publications
- Myer, Robert O. and Daniel W. Gorbet. 2004. Crystalline amino acid supplementation of grain sorghum based low protein diets for growing-finishing pigs. J. Appl. Anim. Res. 25:85-90.
|
Progress 10/01/02 to 10/01/03
Outputs
A study is ongoing to determine the effect of rearing environment/season (hot, humid/summer or thermoneatral/fall) on performance, and on resulting carcass lean content of finishing swine fed traditional or reduced protein, amino acid supplemented diets. During the past year, two trials were conducted and each involved 84 finishing pigs (equal number of barrows and gilts). One trial was conducted during the summer (mid July to mid Sept.) and the other during the fall-winter season (mid Nov. to early Feb.) Within trial, nutritionally adequate corn-based diets (NRC,1998) were formulated with 1) soybean meal (47%) as the supplemental source of amino acids (control) or with 2) L-lysine HCl, L-threonine, DL-methionine and L-tryptophan plus enough soybean meal to meet the requirements of the other amino acids. The amino acid supplemented diets averaged about four percentage units lower in crude protein concentration than the corresponding control diets. The feeding period
was divided into two phases (Finisher I and II ). The pigs were housed in an open sided building in pens with floors that were 20% solid and 80% slotted concrete. Pen space per pig was 0.8 m2. Each pen had an overhead water sprinkler that sprinkled water over the rear half of the pen. The sprinklers were on continuously whenever the temperature exceeded 24 C. During the trials, outside temperature and RH averaged 26 C (range 18 to 34 C) and 84%, and 13 C (-4 to 29) and 77% for the summer and fall trials, respectively. Results indicated that pigs reared during the summer grew much slower (0.88 vs 1.04 kg/d; P<.001) than during the fall. Dietary treatment also affected growth rate in that pigs fed the low protein, amino acid diets overall grew slower (0.94 vs 0.97 kg/d; P < .05) than pigs fed the control diets. There was evidence for a season by diet type interaction (P < .01); pigs fed the low protein, amino acid diets grew slower during the summer than pigs fed the control (0.84 vs
0.92 kg/d); however, no effect due to diet type was noted during the fall (1.04 vs 1.03 kg/d). Feed efficiency (F/G) and estimated carcass lean (ultrasound) were not affected by season or diet type. Overall means were 3.28 for F/G and 51.7% (fat free) for carcass lean. From these preliminary results we saw no evidence that the feeding of a reduced protein, amino acid supplemented diet type was particularly advantageous during times of hot, humid rearing conditions for finishing pigs.
Impacts
Results could be helpful in finding dietary strategies to help minimize the negative effects of heat stress.
Publications
- Myer, R.O. and R.A. Bucklin. 2002. Effect of season (summer vs fall) and diet nutrient density on performance and carcass characteristics of growing-finishing swine. Transactions of the ASAE 45 (3): 807-811.
|
|