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|September, 2010||Volume 33, Number 06|
ALTERNATIVE PROTEIN SOURCE FOR NURSERY PIGS
Formulation of diets for nursery pigs requires a tradeoff between utilizing protein sources that are highly palatable and digestible and those that are low cost. While the major concern of the use of animal protein sources in nursery pig diets has been cost, recent concerns over animal health and food safety related to feeding animal products back to food animals have added greater complexity to this issue. These concerns have also spurred research towards improving the quality of plant protein sources for use in diets for newly weaned pigs. Recent work in our Department by Drs. Sung Woo Kim and Eric van Heugten along with their colleagues has examined a fermented soybean meal (FSBM) product for use in diets designed for newly weaned pigs. The FSBM tested was produced by Genebiotech Co. Ltd (Seoul, Korea) by fermenting soybean meal with a fungus (Aspergillus oryzae) that has been used for human food fermentations for centuries. In addition to partially digesting the proteins in the soybean meal, thereby improving their digestibility, the fermentation process also reduced the concentrations of several anti-nutritional compounds found in soybean meal (Table 1).
Drs. Kim and van Heugten conducted four separate feeding trials to examine the potential for using FSBM instead of animal protein products such as dried skim milk and plasma protein. From the results of these studies, they concluded that the FSBM was superior to soybean meal for inclusion in weaning pig diets. They also demonstrated that this product has the potential to replace dried skim milk, particularly if lactose and synthetic amino acids are utilized. Overall, this work provides valuable information regarding the suitability of FSBM for use in newly weaned pig diets.
Maintaining the barrier function of the intestine is tantamount to maintaining the health and productivity of pigs at weaning. Properly functioning intestinal tissue acts as a selective barrier to allow nutrients in and to keep pathogens and antigens out. Loss of this barrier function increases the pigs’ susceptibility to intestinal infections and increases the energy utilized to mount an immune response. Stress reduces the barrier function of the intestine; however, the mechanism by which this occurs is unclear. The role of stress-induced loss of barrier function is of particular importance to newly weaned pigs, because the weaning process causes both physical and psychological stress. Additionally, intestinal disturbances that occur while the intestine is still developing may have even longer lasting consequences. Recent work conducted at the College of Veterinary Medicine by Dr. Adam Moeser and his collaborators examined the impact of weaning age on intestinal barrier function. A clear effect of increasing weaning age decreasing intestinal permeability was seen in this study (Figure 1). What was most interesting about this impact of weaning age on intestinal permeability was that differences were still apparent over 5 weeks after weaning (Figure 2). This suggests that just a few days difference in weaning age can have effects on the intestinal health of pigs throughout the nursery.
Dr. Moeser and his research group also identified a potential mechanism for the loss of barrier function that was seen with earlier weaning ages. They found that a type of immune cell (Mast cell) was found in greater numbers in the intestinal epithielium of early weaned pigs and that signaling of corticotrophin-releasing factor through these Mast cells may result in the loss of barrier function. By elucidating the mechanism by which stress-induced loss of intestinal barrier function occurs, Dr. Moeser hopes to identify novel methods to ameliorate this condition. For now, it is clear that increased weaning age has potential for improving lifetime intestinal health.
While Environmental Protection Agency regulations limiting the amount of phosphorus (P) in swine effluent have driven research towards finding ways to reduce the excretion of P by pigs, the increased cost of dietary inorganic P sources has continued to motivate producers to reduce the levels of inorganic P added to swine diets. In a recent study conducted by Dr. Chad Stahl and his colleagues, the impact of a single nucleotide polymorphism (SNP) on dietary P utilization was examined. The SNP in the calcitonin receptor gene (CALCR) had been previously identified by Dr. Stahl’s group as being associated with bone integrity in young pigs, so in this study they examined whether there was an interaction between dietary P level and this SNP. Pigs were separated based on genotype and fed either a P-adequate diet (meeting NRC P requirements) or a 20% P deficient diet from weaning until completion of the study 14 weeks later. While there was no impact of genotype or dietary P on growth performance parameters, there were significant interactions between CALCR genotype and dietary P concentrations on measures of bone integrity (Figure 1). Bones of pigs fed the P deficient diet had reduced bone strength and mineral content. Interactions between CALCR genotype and dietary P levels were observed in bone modulus and ash percentage. The metacarpals of pigs with the 11 genotype exhibited greater decreases in bone rigidity (modulus) during P restriction when compared with pigs having the 12 or 22 genotype. The effect of the CALCR genotype on the loss of bone integrity due to dietary P deficiency seemed to be additive, with pigs of the 11 genotype having a greater loss of bone rigidity and mineral content than those having the 22 genotype, and the 12 genotype being intermediate and not different from the other genotypes. The allele 2 of this CALCR SNP was associated with less sensitivity to dietary P restriction, with the bones of the pigs homozygous for this allele not being affected by dietary P deficiency. Because proper bone health plays a major role in the economic viability of swine production, utilization of this data may offer possible management strategies based on the interaction of the CALCR polymorphism and diet to improve sow longevity and gilt development. Although selecting for this particular genotype may not be economically plausible, it may be beneficial to alter the diets fed to animals based on genotype to maximize muscle and skeletal growth potential.
This research is reported in its entirety as “A calcitonin receptor (CALCR) single nucleotide polymorphism is associated with growth performance and bone integrity in response to dietary phosphorus deficiency” J. Anim. Sci. 2010. 88:1009–1016. To request a reprint of this article, or for specific questions regarding this research, contact Dr. Chad Stahl (email@example.com).
Increasing behavioral estrus strength is expected to offer several economic benefits to producers. Strong visible symptoms of estrus should result in reduced missed heat cycles, decreased nonproductive sow days, and increased pigs per sow per year. Additionally, easily detectable estrus symptoms would reduce inappropriate culling for reproductive failure actually caused by missed heat detection. Drs. Joe Cassady and Todd See along with their collaborators conducted a study to develop methods for measuring estrus in swine and to estimate variance components for genetic correlations among these variables and production traits. They identified several indicators that could be incorporated into breeding programs but felt that length of estrus and/or age at puberty (or a similar trait, such as age at first mating or age at first farrowing) are the most promising of the estrus traits they measured to incorporate into current selection schemes. They do caution that before implementing selection programs for estrus traits, economic values should be calculated and correlations with sow reproductive performance should be estimated.
This research is reported in its entirety as “Estimates of variance components for genetic correlations among swine estrus traits” J. Anim. Sci. 2010. 88:2913–2919. To request a reprint of this article or for specific questions regarding this research, contact Dr. Joe Cassady (firstname.lastname@example.org).
This issue of Swine News was compiled and edited by Dr. Chad Stahl. If you would like to provide feedback, he may be contacted at email@example.com