National Animal Disease Information Service –
There are a limited number of worm parasites that affect the pig in the UK. The most prevalent of these is Ascaris suum, most commonly associated with milk spot liver. Over the last 11years producers have had access to abattoir reports clarifying questions regarding milk spot liver condemnation and the need for control of the disease on farm. Fig 3 Intestinal section completely blocked with Ascaris suum worms – an extremely rare occurrence in growing pigs. The adult worm – which can be up to 40cm long – lives in the small intestine of the pigs; in sows there may only be a few of these worms present. There is reason to believe that the sucking pig receiving milk is resistant to these larvae but the eggs can easily be picked up in the farrowing area, stuck to the body and then mature and infect after weaning. Migration through the lungs can present as coughing in growing pigs – impossible to differentiate from enzootic pneumonia and the lungs may contain petechial haemorrhages throughout the tissue at slaughter although this is often grossly obscured by other pathological lesions and slaughter process artifacts. With very heavy infestation in growing pigs, the young mature worms can block the intestine leading to vomiting, constipation, jaundice, weight loss and death. Figure 6 Maturing young adult worms from the gut of a clean pig at slaughter. Pigs affected in this way must have been initially infested earlier in life to allow complete migration and the full life cycle. BPHS reports and to a lesser extent CCIR feedback provide a reliable monitoring system for the levels of parasitism in slaughter pigs. Abattoir data collected as part of the Batch Pig Health scheme indicates that up to 90% of herds show no evidence of milk spot livers at slaughter and less than 5% of herds have significant levels of livers affected. The vast majority of batches of slaughter pigs show no evidence of milk spot suggesting the husbandry system is sufficient to maintain full control of the parasite or any challenge occurs early in life and lesions have resolved. The most likely scenario is where cats contaminate growing pig environments and the cat roundworm -Toxocara cati – sheds eggs that can produce larvae to be picked up by the pigs. Where treatment of growing pigs proves necessary, it is important that the product chosen is effective against the larvae as well as the adults. Abattoir data collected as part of the Batch Pig Health scheme indicates that approximately 70% of herds show no significant evidence of milk spot livers at slaughter and only 5-8% of herds have an incidence of more then 25% livers affected.
Impact and Use of Paylean in Market Pigs
The implementation of lean value carcass pricing systems has led to the selection of pigs with increased lean growth rates, increased carcass lean percentages and improved lean feed conversion. Paylean increased daily fat-free lean gain by an average of 34% for pigs fed 20 ppm and 23.3% for pigs fed 10 ppm for the last 90 lb. The percentage lean growth responses to Paylean are consistent across genotypes with different lean growth potentials. Two studies consisting of seven genotypes with substantially different lean growth rates fed 20 ppm Paylean resulted in a consistent 34% increase in lean gain regardless of genotype. Greater Paylean lean growth responses will occur in pigs of high lean growth genotypes. In other words, Paylean complements genotypes with high lean growth potentials by increasing their advantage over average genotypes by an additional 34%. Paylean does not have the same effect on different carcass measurements. The daily fat-free lean growth rate for a high lean growth genotype fed 0, 10, or 20 ppm Paylean is shown in figure 2. Live weight, Paylean increases daily fat-free lean growth rate at a time when lean growth is normally decreasing, especially for low-medium lean growth genotypes. Feeding Paylean repartitions nutrients away from fat growth towards lean growth. Pigs fed Paylean can achieve 34% higher maximum daily fat-free lean growth rates with lower energy intakes than those needed for conventional pigs to achieve their lower lean growth rates. Last-rib backfat is the least accurate measurement in predicting the lean mass of Paylean fed pigs. The actual fat-free lean advantage predicted by a pork processor is going to be affected by a number of factors including; the accuracy of the data and measurements used in the development of the equation; the inclusion of Paylean fed pigs in the data set used to develop the equations; the technologies used to predict lean mass and accuracy of the measurements in the pork processing plant; and the relative emphasis the equations place on measure of muscle mass including loin depth, loin eye area, and TOBEC values. The Paylean advantage is not a constant but is affected by the level of Paylean fed, the duration of feeding before market, lysine level in the diet, and genetic potential for lean growth. Pigs fed Paylean show large advantages in terms of lean growth, lean feed conversion, and carcass lean percentage. The amount of the increase in fat-free lean mass as predicted from carefully collected measurements and prediction equations as a percentage of the actual increase in fat-free lean mass in pigs fed Ractopamine.