EFFECT OF BETA-MANNANASE ENZYME ADDITION TO SOY-CONTAINING MILK REPLACERS ON GROWTH AND HEALTH OF NEONATAL DAIRY CALVES

Abstract

The increasing cost of milk proteins is forcing the milk replacer industry to evaluate alternative protein sources to make more cost effective products. Alternative proteins should contain an appropriate amount of crude protein that is digestible with an adequate amino acid profile. Among the available protein sources, soy protein appears to be good alternative because of the protein content, availability, and lower cost compared with the milk proteins. However, soybean contains anti-nutritional factors such as trypsin inhibitor, lectins, and non-starch polysaccharides and inclusion of soy proteins in milk replacer has resulted in reduced growth and health in preruminant calves. The use of exogenous enzymes such as mannanases in poultry and swine has shown improved performance in the digestibility of soy-based feeds. The aim of this study was to evaluate the effects of soy-containing milk replacer with the addition of mannanase-based enzymes on growth and health of pre-ruminant Holstein bull calves. Two milk replacers were used for this experiment, a commercially available whey based milk replacer (28% CP and 15% fat) and a specially formulated soy protein containing milk replacer with fifty percent of the protein replaced by the soy protein concentrate. Fifty-six calves (n=14 per treatment, four treatments) were assigned to treatments consisting of either the all whey protein, or the soy protein milk replacer without mannanase based enzymes or two additional treatments fed two concentrations of mannanase based enzymes. The calves were provided 0.28 Mcal gross energy/kg BW0.75 the first seven days and 0.32 Mcal gross energy/kg BW0.75 until day 21 when the absolute amount was held constant to maintain adequate inventory of milk replacer for the 56-day study. On day 36 a commercial calf starter was provided to the calves on an ad libitum basis, and a step down weaning process weaning occurred at day 56 with complete starter removal and weaning by day 63. Initial (53.6 +-6.4 Kg) and final (111.2 +- 10.7 Kg) body weights were not significantly different, thus average daily gain (0.91 +-0.14 kg/d) was not different among treatments. Among treatments, dry matter intake (1.64 +-0.25 kg/d) and overall feed efficiency (gain:feed, 0.56 +-.07) was not different. Differences were not detected among treatments for health, fecal score and body condition score (P > 0.10). A cost analysis was conducted and the cost per kilogram of gain of calves fed the soy protein concentrate milk replacer with the mannanase based enzymes was approximately 30% lower than calves fed the whey based milk replacer. Therefore, in this experiment, the use of soy protein concentrate with the mannanase-based enzymes provided similar animal performance as whey proteins and decreased the cost of production.