A pig growth assay was conducted to determine the relative biological value (RBV) of lysine from L-lysine sulfate relative to feed grade lysine·HCl. A maize-peanut meal diet containing 6.2 g/kg total lysine was supplemented with 2 levels (1 and 2 g/kg) of lysine from L-lysine·HCl or L-lysine sulfate. The RBV of L-lysine sulfate was determined using multiple regression slope-ratio methodology, with gain and feed efficiency as the response criteria. At the tested levels, linear responses for gain and feed efficiency were obtained from increments of lysine from the two lysine sources. When weight gain was regressed on supplemental lysine intake, the RBV of lysine in L-lysine sulfate was 99% of the RBV of lysine in L-lysine·HCl. For feed efficiency was regressed on supplemental lysine intake, the RBV of lysine in L-lysine sulfate was 97% of the RBV of lysine in L-lysine·HCl. The t-test analysis revealed that the RBV of lysine in L-lysine sulfate was not significantly different from the RBV of lysine in L-lysine·HCl, which was assumed to be 100% bioavailable.

When comparing RDA (Recommended Dietary Allowances, NRC, 1989) values for adult humans with daily requirement estimates for adult boars, gestating sows and late-finishing pigs (NRC, 1998), several items stand out. In general, based on body size and weight, bone structure, and physiological function and activity, one might assume that, with some exceptions, daily requirements of adult and near-adult swine should exceed daily human requirements by 2- to 3-fold. Do they? And what do these comparisons reveal?

Improvements in carcass leanness to meet consumer demands for lean meat has also resulted in a reduction in intramuscular fat which potentially has a negative effect on the palatability of pork. A number of approaches have been investigated to increase intramuscular fat by manipulating nutrients in diets including feeding protein deficient diets (Castell et al., 1994; Blanchard et al., 1999) and high dietary leucine levels (Cisneros et al., 1996). Leucine is a ketogenic amino acid, the carbon skeleton of which is converted to acetyl-CoA and acetoacetate in muscle tissue and those intermediates can be used to synthesize fatty acids. In the study of Cisneros et al. (1996), high dietary leucine also resulted in an improvement in muscle color.

A number of studies have reported that feeding supra-nutritional levels of magnesium in the diet improves pork quality (D'Souza et al., 1998; D'Souza et al., 1999; Hamilton et al., 2002). However, the optimum source, time of feeding and level of magnesium supplementation necessary to improve pork quality has not been established. The current study was carried out to investigate the effects of source, time of feeding and level of supplemental magnesium on pork quality.

The soybean is known as an excellent source of protein when formulating diets for swine.  However, this potential can be achieved only if certain quantity of heat is applied. Osborne and Mendel (1917) were the first to report that raw soybeans had a growth-depressing effect in rats.   Generally, these heat labile factors are protease inhibitors, lectins, goigotrens and antivitamins.  The most common way of eliminating these factors is by heating or “toasting” the soybeans in a processing plant, being sure that temperature, duration of the heating, particle size and moisture are controlled. Another way to inactivate these factors is by dry extrusion (without steam). 

Most of the work done on the isoleucine (Ile) requirement of pigs was done 30 to 50 years ago and involved pigs with limited potential for lean growth. Moreover, validation of Ile-deficient assay diets was seldom carried out, and often the experimental pigs were limit fed rather than full fed. Also, energy and protein levels of assay diets was different from the levels used in practice, and Ile digestibility of the basal diets was not known. Thus, recent estimates of the Ile requirement of pigs (NRC, 1998) was based on (calculated) factorial estimates rather than on empirical evidence.

While new swine production technologies are making inroads into controlling many swine pathogens, Haemophilus parasuis-induced disease has unexpectedly emerged as an increasing problem (Nicolet, 1992; Boeckman, 1995; Radle, 1996; Zimmerman et al., 1997; Rapp-Gabrielson, 1999; Dee, 2000). Innovative new strategies of disease control are needed to meet the challenges associated with new production technologies for high health herds, including segregated early weaning and all-in all-out pig flow in production facilities.

Fumonisins are a group of naturally occurring mycotoxins produced by the fungus Fusarium verticillioides (previously moniliforme). Fumonisin B₁ (FB1), is the most common toxin produced. Fumonisins alter sphingolipid biosynthesis, induce hepatotoxicity, and elevate serum cholesterol concentration in all species studied including pigs, calves, lambs, mice, rats, mink, and broiler chicks. A major concern for humans ingesting fumonisin contaminated food is the cardiotoxicity and hypercholesterolemia observed in swine and nonhuman primates. In swine, the heart is the primary target organ of fumonisin toxicity, with lethal pulmonary edema (PPE) occurring secondary to heart failure (Smith et al., 1996a and b; Haschek et al., 2001; Constable et al., 2000; Smith et al., 2000). Hypercholesterolemia was reported as the earliest detectable change in serum of swine following ingestion of fumonisin B₁ at concentrations as low as 1 ppm (Rotter et al., 1996). Fumonisin B₁ does not change cholesterol secretion (Merrill et al., 1995) but may change lipid metabolism (Rotter et al., 1997). FB1 alters sphingolipid biosynthesis by inhibiting sphingosine N-acyltransferase and sphinganine N-acyltransferase and results in increases in the sphingoid bases, sphinganine and sphingosine, and depletion of complex sphingolipids (Wang et al., 1991, Yoo et al., 1996). It has been hypothesized that the mechanism of action of fumonisin is through these alterations in sphingolipid biosynthesis.

Variation in piglet weights within a group at weaning can impact the productivity of commercial pig production systems, particularly those implementing all-in all-out animal management. Weaning weight has been shown to be closely related both to birth weight (Wolter and Ellis, 2001) and the amount of sow's milk consumed by the piglet during lactation (Lewis et al., 1978). Providing piglets with supplementary liquid milk replacer during lactation can increase weaning weights (Azain et al., 1996; King et al., 1998). However, the impact of increasing the weaning weight of pigs using supplemental liquid milk replacer on subsequent performance to slaughter weight has not been established. Therefore, the objective of the current study was to evaluate the effect of weaning weight as affected by birth weight and feeding a supplemental liquid milk replacer diet during lactation on pig performance from weaning to slaughter weight.

Phytoestrogens are natural plant-derived endocrine modulators which have a range of demonstrated and hypothesized effects. They may have potential as important health factors in prevention of estrogen dependent cancers and cardiovascular disease; and they may modulate postmenopausal symptoms (Davis et al. 1999). Soybeans are a principle source of phytoestrogens, containing at least three isoflavones, genistein, daidzein and glycitein, of which genistein is present in the greatest quantities (Wang and Murphy 1994a). The estrogenic activity of phytoestrogens can have significant effects on estrogen-sensitive reproductive tissues (Kaldas and Hughes 1989). For example, removal of endogenous estrogen by removing the ovary in rats and treatment with microgram doses of genistein or the non-soybean phytoestrogen coumestrol results in increased uterine size by 60 or 75%, respectively, within six hours (Perel and Lindner 1970). In another example, immature rats exposed to coumestrol, either in the diet or by parenteral injection, experience significant increases in uterine weights (Whitten et al. 1992). Feeding genistein to ovariectomized post-pubertal rats also can have a dose-dependent increase in uterine development (Santell et al. 1997). Feeding ovariectomized ewes a diet containing phytoestrogens also can result in uterine weight increases (Nwannenna et al. 1995).