Genotype has the greatest influence on pig performance whereas improvements due to vaccination against PCV2 is dependent on herd health status
Take Home Message: Focus on pig genotype to improve growth rate and carcass composition with benefits due to vaccination dependent on herd health status
Genotype has the greatest influence on pig performance – in terms of growth rate and body composition – even when a vaccine against Porcine circovirus type 2 (PCV2) is used. In trials carried out at Leeds University, comparing vaccinated and non-vaccinated pigs, Hampshires performed better than Large Whites in terms of average daily gain (ADG) and age at slaughter due to a higher intake and required less antibiotic treatment.
“But there was no difference in FCR between genotypes. And although growth performance was better for Hampshires, Large Whites were, in fact, leaner at slaughter,” Leeds University’s Amy Taylor told delegates at this year’s British Society of Animal Science annual conference. “And there was no difference in body composition between vaccinated and non-vaccinated pigs.”
Disappointingly, her team’s work showed that vaccination against PCV2 had no significant effect on growth performance or health status. “But pigs moved buildings at 15 weeks of age so the higher ADG seen for vaccinated pigs at 16 weeks may indicate that non-vaccinated pigs were less tolerant to the stresses involved,” she added.
A lower mortality rate was seen throughout the trial compared to previous years suggesting that on farm disease may have been lowered as a result of half the pigs on farm being vaccinated against PCV2.
Crossbreeding is common practice in commercial pig production as one way to increase lean growth and improve meat quality. And reducing disease is another way to help improve growth rate in pigs.
Porcine circovirus type 2 has devastated the pig industry in recent years. PCV2 infection increases mortality and reduces growth rate as it acts as an immunosuppressant thereby making pigs more susceptible to co-infections.
“Keeping disease at low levels has been achieved by improving husbandry standards, biosecurity, minimising presence of other pathogens and use of antibiotics. However vaccines against PVC2 are now available,” said Miss Taylor, explaining the rational behind the study, to investigate the effects of sire genotype and PCV2 vaccine on growth performance and body composition of pigs.
The trial compared sire genotypes (Hampshire and Large White) and vaccination status (vaccinated or not).
A total of 264 pigs were weaned at 28±4 days. Within each litter half of the pigs were vaccinated against PCV2 at three weeks of age. Pigs were then allocated to pens based on their genotype and vaccination status and balanced for weight and sex. Pigs were individually weighed at weaning and then at five, six, seven, 10, 12, 14, 15, 16, 17 and 22 weeks of age and prior to slaughter.
Weekly pen feed intakes were recorded and feed conversion ratios (FCR) calculated throughout the trial. All pigs were given daily health checks, recording any ill health. And pigs were scanned for body composition at slaughter.
Throughout the trial the Hampshires had a higher average daily intake (ADI) and average daily gain (ADG) when compared to Large Whites. There was no difference in FCR between genotypes and vaccination had no effect on growth performance.
But ADG at week 16 was higher for vaccinated pigs compared to their non-vaccinated counterparts.
“Although there were no significant differences in mortality between treatments, mortality as a whole was down by 9.3% compared to on-farm mortality over previous years,” said Miss Taylor.
Due to a faster growth rate, Hampshires were 8.4 days younger at slaughter, but Large Whites were leaner at slaughter. Vaccinated pigs were, on average, 2.2 days younger at slaughter. “No differences in carcass composition between vaccinated and non-vaccinated pigs were found,” she added.
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