Non-ruminant Livestock Research Articles

Manipulation of the Repertoire of Digestive Enzymes Secreted into the Gastrointestinal Tract of Transgenic Mice

In non-ruminant livestock the energy which can be derived from dietary cellulose and xylan is limited by the inefficient microbial fermentation of these polymers in the hind-gut. Furthermore, in poultry, cereal-derived plant structural polysaccharides impair normal digestive function through the formation of gel-like structures, which trap nutrients rendering them unavailable to the animal. The nutrition of non-ruminant livestock could be significantly improved by the depolymerization of plant structural polysaccharides, through the introduction of cellulase activity into the small intestines of these animals. Here we describe the expression of Clostridium thermocellum endoglucanase E in the exocrine pancreas of transgenic mice. A non-glycosylated active enzyme is secreted into the small intestines, and is resistant to proteolytic inactivation, demonstrating the feasibility of generating non-ruminant animals with the endogenous capacity to depolymerize plant structural polysaccharides in the small intestines.

The generation of non-ruminant transgenic animals with cellulolytic capacity.

In non-ruminant livestock the energy which can be derived from dietary cellulose and xylan is limited by the inefficient microbial fermentation of these polymers in the hind-gut. Furthermore, in poultry, cereal-derived plant structural polysaccharides impair normal digestive function through the formation of gel-like structures that trap nutrients which are therefore unavailable to the animal. The nutrition of non-ruminant livestock could be significantly improved by the depolymerization of plant structural polysaccharides, through the introduction of cellulase activity in the small intestines of these animals. This report describes the generation of transgenic animals with the capacity to express and secrete a functional endoglucanase from the exocrine pancreas.The gene encoding endoglucanase E (celE) from Clostridium thermocellum was fused to the exocrine pancreas specific enhancer of the elastase I gene and the (β-globin polyadenylation signal, and used to create 14 lines of transgenic mice. A range of tissues were assayed for cellulase activity, using β-glucan and 4-methylumbelliferyl-β-D-cellobioside as substrates. The pancreas was also subjected to immunohistochemistry and in situ hybridization.

Lysine and Protein Content of Normal and Opaque‐2 Maize Grain as Influenced by Irrigation and Nitrogen

Increasing soil N fertility has been found to have detrimental effects on the nutritional quality of maize (Zea mays L.) grain; however, little research has evaluated the effects of irrigation on these factors. Most previous work has been done with inbred lines rather than high‐yielding commercial hybrids. This study was conducted to determine how irrigation and soil N levels would affect the content of protein and lysine plus the quality of maize protein as measured by the lysine in protein (LP). Two water regimes and five soil N levels were applied to two normal and two opaque‐2 commercial hybrids grown on a Sharpsburg silty clay loam soil (fine, montmorillinitic, mesic Typic Argiudoll). The hybrid ✕ year interaction indicated that in 1985 and 1987 the short‐season opaque‐2 hybrid (SO) had a greater yield than the short‐season normal hybrid (SN) by ≈8%, whereas the long‐season normal hybrid (LN) had a greater yield than the long‐season opaque‐2 hybrid (LO) by 4 to 12%. In 1986, normal and opaque‐2 hybrids produced similar yields. Irrigation increased yield, decreased protein content (PT) 5 to 7 g kg‐1, and increased LP by 1 to 2 g kg−1 in 1985 and 1986. Irrigation also decreased lysine in sample (LS) 0.3 g kg−1 for opaque‐2 grain. Conversely, increasing soil N levels increased yield, PT, and LS, while LP decreased quadratically from 0.39 to 0.36 % kg−1. Grain yield was maximized by production of LN hybrids with irrigation and high soil N levels. The highest PT levels were produced with normal hybrids with high soil N levels without irrigation. Grain produced by opaque‐2 hybrids under low soil N conditions without irrigation had the best protein quality as indicated by LP. Results from the study indicate that both grain yield and nutritional quality are influenced by hybrid selection, irrigation, and N fertilization, which should be considered by producers of nonruminant livestock.

Effect of Aspergillus oryzae fermentation extract (Amaferm) on fermentation in the rumen simulation technique (Rusitec)

Probiotics (microbial preparations and their growth media) are of increasing interest as feed additives for both ruminant and non-ruminant livestock. Amaferm is a fermentation extract prepared from cultures of the fungus Aspergillus oryzae which, when included in the diet of dairy cows, increases the yield of milk and buttermilk (Harris et al. , 1983). These improvements have been associated with changes in rumen fermentation (Weidmeier et al., 1987). The present study describes the use of the rumen simulation technique Rusitec (Czerkawski and Breckenridge, 1977) to investigate the effects of increasing doses of Amaferm on the stoichiometry of rumen fermentation in vitro.Amaferm was added at 0, 25 and 250 mg/d to duplicate Rusitec vessels and at 1 g/d to a single vessel, receiving 10 g/d of a mixed diet of hay, barley, molasses, fishmeal and vitamins/minerals (500, 299-5, 100, 91 and 9.5 g/kg DM respectively). Vessels were initially inoculated from animals receiving the same diet. Artificial saliva was continuously infused into the vessels (total volume 850 ml, dilution rate 0.88/d) and feed bags were changed daily such that each bag was incubated for 48 h. Samples were taken at the time of feeding after 15 d adaptation to Amaferm.Amaferm had no influence on total VFA concentrations but there was a shift towards an increased proportion of butyrate as the level of addition increased. Ammonia production was also stimulated by the addition of Amaferm, with the concentration in the vessel receiving 1 g/d being almost twice that found in the control vessels. There was no effect on dry matter disappearance after 48 h. The concentration of methane in the gas collected from the head space of the vessels was decreased by Amaferm, with the maximum decrease (17%) being seen at the level of 250 mg/d.