Monthly Archives: August 2010

This manuscript focuses on the advances made using genomic approaches to identify biomarkers that define genes and pathways that are correlated with swine resistance to infection with porcine reproductive and respiratory syndrome virus (PRRSV), the most economically important swine viral pathogen worldwide. International efforts are underway to assess resistance and susceptibility to infectious pathogens using tools such as gene arrays, single nucleotide polymorphisms (SNPs) chips, genome-wide association studies (GWAS), proteomics, and advanced bioinformatics. These studies should identify new candidate genes and biological pathways associated with host PRRS resistance and alternate viral disease processes and mechanisms; they may unveil biomarkers that account for genetic control of PRRS or, alternately, that reveal new targets for therapeutics or vaccines. Previous genomic approaches have expanded our understanding of quantitative trait loci (QTL) controlling traits of economic importance in pig production, e.g., feed efficiency, meat production, leanness; only recently have these included health traits and disease resistance. Genomic studies should have substantial impact for the pig industry since it is now possible to include the use of biomarkers for basic health traits alongside broader set of markers utilized for selection of pigs for improved performance and reproductive traits, as well as pork quality. Additionally these studies may reveal alternate PRRSV control mechanisms that can be exploited for novel drugs, biotherapeutics and vaccine designs.

Crossbred pigs (n = 216; BW = 31.3 ± 1.8 kg) were used to determine the effects of long- and short-term feeding of crude glycerol on growth performance, carcass traits, and pork quality of grow-finish pigs. Pigs were blocked by initial BW, and pens within blocks were assigned randomly to 1 of 3 dietary treatments (24 pens; 9 pigs/pen). Dietary treatments were: control, a corn-soybean meal based diet (CON); long-term, CON + 8% glycerol fed throughout the experiment (LT); and short-term, pigs fed CON for the first 6 wk followed by CON + 8% glycerol fed during the last 8 wk of the experiment (ST). Pigs fed LT had higher (P < 0.05) ADG, while pigs fed ST tended (P < 0.10) to grow faster than CON (CON = 0.962 kg/d, LT = 0.996 kg/d, and ST = 0.992 kg/d; SE = 0.01). Pigs assigned to LT had greater (P < 0.05) ADFI compared to CON, while ST-fed pigs had similar ADFI to CON (CON = 2.78 kg/d, LT = 2.93 kg/d, and ST = 2.86 kg/d; SE = 0.03). Gain:feed tended (P < 0.10) to be greater for CON- and ST-fed pigs compared to LT-fed pigs (CON = 0.346, LT = 0.339, and ST = 0.346; SE = 0.002). Hot carcass weight was greater (P < 0.05) for LT-fed pigs compared to CON, while ST-fed pigs had HCW similar to both LT- and CON-fed pigs (CON = 94.8 kg, LT = 97.5 kg, and ST = 96.3 kg; SE = 0.90). Dressing percentage of CON-fed pigs was similar to both LT- and ST-fed pigs, but LT-fed pigs tended to have higher (P = 0.06) dressing percentage than ST-fed pigs (CON = 74.5%, LT = 74.9%, and ST = 74.3%; SE = 0.16). Tenth rib backfat and LM area were not affected by dietary treatment. There was a trend (P < 0.10) for LT-fed pigs to have lower fat-free lean percentage than CON fed pigs (CON = 53.1%, LT = 52.26%, and ST = 52.67%; SE = 0.25). Short-term glycerol feeding increased (P < 0.05) belly firmness compared to CON, and had similar belly firmness compared to LT-fed pigs (CON = 29.46°, LT = 35.16°, and ST = 42.08°; SE = 3.07). Dietary treatment had no effect on pork quality of loins based on taste panel assessments. Feeding pigs 8% crude glycerol throughout the grow-finish period resulted in a 3% improvement in growth rate and a 2% depression in gain efficiency compared to control diets. Grow-finish pigs fed diets containing 8% crude glycerol during the last 8 wk before harvest achieved growth performance similar to pigs fed control diets. Effects of crude glycerol on carcass traits seem to be limited to improvements in belly firmness with short-term feeding of glycerol.

The objective of this trial was to determine the effect of age at first estrus on BW changes and long-term reproductive performance of sows. At approximately 100 d of age, prepubertal C22 gilts (n = 431) were allocated to trial. At a pen average of 140 d of age, gilts began daily direct contact with mature boars to stimulate onset of puberty. Gilts (n = 317, 73%) were recorded as cyclic by 180 d of age (select) and were classified on the basis of age at puberty into 3 puberty groups: 1) early puberty (EP;