R. C. Ewan

Short-term feeding of vitamin D3 improves color but does not change tenderness of pork-loin chops.

The objective of this study was to determine the effect of short-term feeding of vitamin D3 (D3) on blood plasma calcium concentrations and meat quality of pork-loin chops. Three experiments were carried out to meet this objective. Experiment 1 used 250,000 IU and 500,000 IU/d to determine the effective dose of dietary D3 to raise blood plasma calcium concentration. Experiment 2 used 500,000 IU D3/d to determine the appropriate length of feeding time to elevate blood plasma calcium prior to harvest. Experiment 3 used 500,000 IU D3/d to determine the effectiveness of increased blood plasma calcium in improving postmortem quality and tenderness of pork-loin chops. Pigs fed 500,000 IU D3/d in Exp. 1 exhibited higher (P < 0.05) and more stable plasma calcium concentration over a 14-d feeding trial compared with pigs fed 250,000 IU D3/d and control pigs. Therefore, 500,000 IU D3/d was the dose chosen for Exp. 2, in which pigs fed 500,000 IU D3/d for 3 d prior to harvest exhibited elevated and stable plasma calcium concentrations; this length of time was deemed sufficient in which to observe differences in postmortem meat tenderness in Exp. 3. Vitamin D3 supplementation resulted in lower (P < 0.02) L* values and higher (P < 0.03) a* values of loin chops at 7 and 14 d of shelf storage. Vitamin D3 supplementation did not affect quality characteristics (measured by use of subjective scores) or tenderness (quantified via Warner-Bratzler shear force or Star probe values). On the basis of these findings, feeding 500,000 IU D3/d to finishing pigs improved most Hunter color values at 14 d of storage but did not improve pork-loin chop tenderness at 1 to 21 d of retail shelf storage.

The addition of ground wheat straw as a fiber source in the gestation diet of sows and the effect on sow and litter performance for three successive parities.

A regional experiment was conducted at 8 experiment stations, with a total of 320 sows initially, to evaluate the efficacy of adding 13.35% ground wheat straw to a corn-soybean meal gestation diet for 3 successive gestation-lactation (reproductive) cycles compared with sows fed a control diet without straw. A total of 708 litters were farrowed over 3 reproductive cycles. The basal gestation diet intake averaged 1.95 kg daily for both treatments, plus 0.30 kg of straw daily for sows fed the diet containing ground wheat straw (total intake of 2.25 kg/d). During lactation, all sows on both gestation treatments were fed ad libitum the standard lactation diet used at each station. Response criteria were sow farrowing and rebreeding percentages, culling factors and culling rate, weaning-to-estrus interval, sow BW and backfat measurements at several time points, and litter size and total litter weight at birth and weaning. Averaged over 3 reproductive cycles, sows fed the diet containing wheat straw farrowed and weaned 0.51 more pigs per litter (P <or= 0.04), and had total litter birth and weaning weights that were 0.87 and 3.59 kg heavier (P = 0.01), respectively, than sows fed the control gestation diet. Sows fed the gestation diet containing wheat straw consumed more (P = 0.01) lactation diet per day than control sows. There were no gestation diet treatment differences for any sow fate criterion (farrowing and rebreeding percentages, and culling rate), any sow BW and backfat measurement, or the weaning-to-estrus interval. Lactation diet intake and all sow BW and backfat measurements increased with increasing parity. In conclusion, when the daily intake of the basal gestation diet was equalized for both treatments, the addition of 13.35% ground wheat straw to the gestation diet improved sow and litter performance, with increases in litter size and total litter weight at birth and weaning compared with control sows and litters.