National Muscle Quality Evaluation

Breeders will be affected as packer and processor payment programs for quality continue to evolve. Breeders should consider how their pork producer customers will market their products in the future when selection priorities are set and selection decisions are made. Results from this test and other muscle quality evaluations show that large differences exist in the industry for most of the muscle quality traits. These differences demonstrate the need for breeders to monitor muscle quality traits, as well as growth and carcass traits, in their breeding programs. Expected Progeny Differences (EPDs) for muscle quality parameters should be used by breeders to place selection emphasis on these traits. Incorporation of them into selection indexes will be a major step in meeting the needs of the pork industry of the future

1998 ISU Swine Business Record Program

Historically low market hog prices resulted in negative returns for nearly all producers in the 1998 ISU Swine Business Record State Summary. Average margin over all costs/cwt of pork produced was negative for all profit groups. Producers in the top 10% and top one-third profit groups achieve the best combination of efficient production levels and lower-than-average production costs. Producers in these profit groups had lower than average production costs/cwt in all feed and nonfeed categories in the 1998 State Summary. These advantages are due to improved management, genetics, and effective implementation of new technologies. Producers in the top 10% profit group had a small advantage in market price received compared with the average of all producers in the program, and a significant advantage over the bottom one-third profit group

Construction of a Model for Prediction of Sows Failing to Express Symptoms of Estrus Within Seven Days Postweaning

Data were compiled and analyzed to identify sows that are most likely to fail to express symptoms of estrus within 4–7 days after weaning. Five variables expected to influence estrus expression in sows were considered. Identification of those sows would allow producers to induce estrus by injection of gonadotropin hormone (PG600) at weaning. In that way reduction of nonproductive days is possible. Genetic line and parity had a significant effect on rebreeding rate in this study. Line C-15 females had significantly lower rebreeding rate when compared to C- 42 and C-22 females. A lower rebreeding rate for first parity females was observed. Administration of gonadotropins to females with a greater likelihood of a prolonged wean to estrus interval and lower rebreeding rate may help to improve reproductive performance of sows and decrease nonproductive days

Influence of Timing of Insemination on Conception Rate and Litter Size in Gilts

Two different genetic lines and three timings of insemination were evaluated to determine the best insemination time for gilts that ensures high conception rate and high number of piglets born in the litter. Different genetic lines may require different timings of insemination

Effect of Beta-carotene on Reproductive Performance in Swine

Injection of beta-carotene did not alter live litter size, total born, number born dead, number of stillborn pigs, and number of mummified pigs in this study. Number of pigs weaned and litter weaning weight also were not significantly different (P\u3e.05). Furthermore, no significant interactions between parity and beta-carotene injection were observed. The commercial herds that were evaluated had already achieved high levels of reproductive performance. Average number of pigs born alive pretreatment was 10.51. These herds were under excellent management and the breeding herd was in superior condition. Perhaps the treatment would be more successful in situations where the sow herds have lower reproductive performance. Use of beta-carotene should be a farm by farm decision, using records to warrant and to verify the effectiveness of betacarotene treatment

Selection for Lean Growth Rate in a Synthetic Line of YorkshireMeishan Pigs 1. Selection Pressure Applied and Direct Response

Selection for lean growth rate (LGR) was conducted for four generations in a synthetic line of YorkshireMeishan pigs. In the select line, seven boars and 20 gilts with the highest LGR were selected from each generation to produce the subsequent generation. A contemporaneous control line was maintained by randomly selecting five boars and 15 gilts to produce the next generation. Inbreeding coefficients averaged .198 and .207 for the select and control line pigs and .173 and .162 for the select and control line dams, respectively, in the fourth generation. LGR was estimated from ultrasound measures of 10 th -rib backfat thickness and longissimus muscle area from 1,057 pigs. These pigs were sired by 58 boars and out of 133 sows. The generation interval was 13 months and the average selection differential per generation was 1.1 phenotypic standard deviation units for LGR. Heritability and response were estimated from the deviation of select line from the control line and multiple trait derivative free restricted maximum likelihood (MTDFREML) on the same material. Realized heritability was .29 ± .12 for LGR in the control line. Corresponding estimates from MTDFREML were .32 and .37. The estimate of direct genetic change per generation using the deviation from the control line was 9.4 g/day for LGR. Corresponding estimates from MTDFREML were similar but were more precisely estimated

Comparison of Grain Sources (Barley, White Corn, and Yellow Corn) for Swine Diets and Their Effect on Production and Carcass Traits

Energy sources differ in content, quality, and availability of nutrients. The objective of this study was to identify and compare differences in production and carcass traits in pigs fed different energy sources. While pigs fed a barley-based diet had a smaller loin muscle area, there was no difference among diets when comparing fat depth or percent fat-free lean. Barley based-diets and a diet containing one-third yellow corn and two-thirds white corn had a lower lean gain per day on test. There was no significant difference in average daily gain or feed-to-gain ratios