Growth performance, carcass characteristics, and meat quality of halothane carrier (Nn) and negative (NN) pigs grown from 40 kg live weight and slaughtered at three weights (110, 125, and 140 kg live weight) were studied. Daily gains were similar for the two genotypes (974 g for Nn and 964 g for NN), but Nn pigs had a higher gain:feed ratio than NN pigs (P < .01). Dressing percentage was higher in Nn pigs than in NN pigs (P < .001), but there were no genotype differences for carcass length, backfat thickness, or loin eye area. Percentage yield of trimmed, boneless wholesale cuts was higher for Nn pigs than for NN pigs (P < .05). This resulted from higher trimmed, boneless ham, boston, and picnic weights (P < .05) in Nn than in NN pigs (6.9, 3.2, 3.5 kg vs 6.6, 3.0, 3.4 kg, respectively). The weight of fat-free lean was higher in Nn pigs (P < .05). The longissimus thoracis muscle from carrier pigs had lower 45 min (P < .001) and 24 h (P < .01) pH. Longissimus lumborum samples from carriers had lower (P < .001) subjective' meat quality scores and a higher drip loss (P < .001); however, cooking loss, eating quality, and shear force values were similar for the two genotypes. There were no important slaughter weight x genotype interactions for the traits reported. Overall, the data from this study suggest Nn pigs had an advantage over NN pigs in terms of feed efficiency, carcass yield fat-free lean content, and commercial lean cut yields but had a higher incidence of PSE.

This study was designed to investigate the effects of dietary lysine level on the intramuscular fat content of the longissimus in finishing pigs reared at two environmental temperatures. Seventy-two hybrid gilts were individually penned and given ad libitum access to either a diet formulated to meet their lysine requirement (6.4 g/kg lysine) or a lysine-deficient diet (4.8 g/kg). Pigs were held at one of two environmental temperatures (thermoneutral [18 degrees C] or hot [32 degrees C]). The study was carried out between approximately 90 and 126 kg live weight; pigs in the thermoneutral and hot environments were on test for 5 and 7 wk, respectively. There were no interactions between dietary lysine level and environmental temperature. Dietary lysine content did not influence feed intake or average daily gain; however, pigs on the lysine-deficient diet had a poorer gain:feed ratio than those fed to requirement (P < .01). High environmental temperature decreased feed intake (P < .001) and average daily gain (P < .01) but improved gain:feed ratio (P < .01). Backfat at the 10th rib was increased and loin eye area and estimated percentage lean in the carcass were decreased for pigs on the lysine-deficient diet. The higher environmental temperature resulted in an increase in carcass length but had no effect on other carcass measurements or intramuscular fat. Feeding the lysine-deficient diet resulted in an increase of .55 percentage unit in longissimus intramuscular fat content (P < .01); however, there was no difference in subjective marbling scores between the diets. Warner-Bratzler shear force values were not affected by dietary lysine level or environmental temperature. Results from this study suggest that feeding of lysine-deficient diets at the end of the finishing period can increase intramuscular fat deposition under thermoneutral and hot conditions.

The feed intake pattern and growth performance of boars, barrows, and gilts fed diets differing in lysine and protein content were measured on 120 crossbred pigs from 27 (SD 3.7) to 81.5 (SD 9.2) kg live weight. The pigs were housed in eight mixed-sex groups with five pigs of each sex in each group. They were fed from an electronic feed station that recorded individual meal sizes and the time and duration of visits to the feeder for each animal in the group. Four dietary treatments were compared. During the grower period (27 to 55 kg), diets ranged in lysine content form .98 to 1.31%; for the remainder of the study, lysine content was .88 to 1.18%. Barrows had a greater (P < .01) number of meals per day than the other two sexes (7.4 vs 7.0 vs 7.0 +/- .10, respectively), but there were no significant differences among sexes for daily feed intake or other feed intake traits. Daily feed intake increased with dietary lysine content, largely because of increased meal sizes resulting from longer feeder occupation times at each visit. Visits to the feeder were greatest between 0900 and 1100 and lowest between 2000 and 0400. Correlations between feeding pattern and growth traits were relatively low. Repeatabilities of feeding pattern traits were generally higher when measured over shorter time periods. These results suggest a change in feeding behavior with increasing dietary lysine levels and a relatively small effect of sex on feeding pattern for mixed-sex groups of 15 pigs fed from a single electronic feed station.

No abstract

A total of 1,034 pigs produced by breeding PIC sows to 2 different PIC terminal sires were used to create 3 distinct weaning weight populations so that postweaning growth to 125 kg could be studied. The rearing strategies resulted in BW that ranged from 4.1 to 11.5 kg by 20 d of age. Sows and corresponding litters were allocated to 3 treatments: sow reared (SR; n = 367) for 20 d, sow reared for 14 d (14W; n = 330), and sow reared for 2 d (2W; n = 337). Sows were removed from 2W and 14W groups, but progeny remained in the crates and received milk replacer ad libitum (for 18 and 6 d, respectively) until the contemporary SR pigs were weaned at 20 d of age. The SR pigs (6.49 +/- 0.15 kg) weighed 1.01 kg less than 14W pigs (7.5 +/- 0.14 kg) and 2.26 kg less than 2W pigs (8.75 +/- 0.14 kg; P < 0.05). The 14W pigs weighed 1.25 kg less than 2W pigs (P < 0.05). Nursery ADG for the 2W group (547 g/d) was 35 g/d less (P < 0.05) than 14W pigs. The 14W pigs (165 d) required 3 fewer (P < 0.05) days to reach 125 kg of BW compared with SR pigs. The SR and 14W pigs gained BW 24 and 20 g/d faster (P < 0.05) in the postnursery period when compared with 2W pigs. The SR and 2W pigs consumed 0.10 and 0.12 kg/d less (P < 0.05) during this period when compared with 14W pigs (2.32 kg/d). Gain:feed of SR was improved (P < 0.05) when compared with the 14W and 2W pigs over 167 d of age (0.44 vs. 0.42 and 0.42, respectively). Lean percentage was 0.7% greater (P < 0.05) in carcasses from SR pigs (55.0%) compared with carcasses from 2W pigs (54.3%) when adjusted to a constant HCW. A study of the effect of weaning weight on days to 125 kg was limited to SR and 14W groups because maternal deprivation compromised the 2W group postweaning growth. Six weaning-weight groups were defined using a normal distribution: 4.6, 5.5, 6.4, 7.3, 8.2, and 9.5 kg. Pigs weighing 5.5 kg at 20 d of age were able to reach 125 kg 8 d sooner (168.8 d) than those weighing 4.6 kg (176.8 d). There was a linear relationship (P < 0.05) between weaning weight and ADG in the postnursery phase of growth. We conclude that 1) a weaning weight of less than 5.0 kg imposes the greatest marginal loss in production output for a 20-d weaning and 2) lactation length influences long-term growth, composition of growth, and viability of progeny.