ARI Volume 2 Number 1.pdf - Zoo-unn.org

UCHEWA, Emmanuel Nwafoagu et al. 272endogenous enzyme production is very rapid,benefits of enzyme addition will be short-lived andof the order of two weeks (Headon and Walsh,1994). α - Amylase addition to a barley diet foryoung pigs improved live weight gain and feedconversion ratio by about 4 %. In grower andfinishing and growing pigs, amylasesupplementation to cereals did not affect pigperformance (Dierick and Decuypere, 1994). Choct(2001) reported significant increase in the liveweight gain and feed conversion efficiency ofchickens fed barley diets. Since it is establishedthat the starch in barley is totally digestible by theamylase secreted by chickens, improvements withamylase supplementation were probably due tothe added enzymes used; i.e. the crude enzymeused contained β - glucanase activity.The effects of added enzymes are greaterin poultry than in pigs and more apparently inyoung than in older animals (Dierick andDecuypere, 1994). However, it is difficult to drawdefinite conclusions. Table 3 shows the meaneffects of simple addition of enzymes to poultryand pigs diets.EFFECT ON THE ENVIRONMENTIn the absence of microbial phytase, onlyapproximately 16 % of phosphorus in corn andapproximately 36 % of phosphorus in soybeanmeal is digested by pigs (Jongbloed et al., 2000).Because of the large amount of undigested dietaryphosphorus, a substantial amount of phosphorus isremoved via the faces. Based on the estimates ofCromwell et al. (1993), a dose of microbial phytaseequal to 1000FTU/g converted approximately onethird of the unavailable phosphorus to an availableform. About 500FTU/Kg of diet generatesapproximately 0.8 g digestible Phosphorus perkilogram of diet, which is equivalent to 1.0 gphosphorus from monocalcium phosphate or 1.23g phosphorus from dicalcium phosphate, which isoften used in the United States.A significant reduction in poultry manurephosphorus can be achieved via the use ofmicrobial phytase in feed. This can reduce thenitrogen: phosphorus ratio in poultry wastes.Blander and Flegal (1997) studied the effect offeed supplemented with allzyme phytase in layerdiets and reported a 16 % reduction in fecalphosphorus from laying hens fed inorganicphosphorus at 80 % of NRC requirements and a25 % reduction in fecal phosphorus from layinghens fed 60 % of NRC requirements. A 35 %decrease in fecal phosphorus from laying hensgiven microbial phytase product at 250 FTU/Kgdiet was reported by Coppoolse et al. (1990).Similarly, Blanda and Flegal (1996) reporteddecreased phosphorus excretion in turkeys givenallzyme phytase. The fecal reductions from layinghens and market turkeys given allzyme phytasesupplemented feeds were similar to thephosphorus reduction found in pigs given anotherphytase feed supplement, (Simons and Versteegh,1992) and broilers (Yi et al., 1996).Conclusion: Many of the environmental impact ofpig farming are known and ultimately controllable.The use of enzymes in pig production is an wellacceptedpractice today. Generally, most of theenzymes effectively depolymerise the soluble NSPinto smaller polymers, though some products withaffinity for both soluble and insoluble NSP are alsoused. It is wise to test economic policy andregulatory changes against the environmentalconsequences and ensure proper planning andimplementation of control measures. That said, itis clear that whilst the potential for damage on theenvironment is great, nutritional manipulation toenhance efficient utilisation of Phosphorus andnitrogen by monogastric animals will reduce thedamage done to the environment by these animalsby at least 30 %.REFERENCESAFRC (1991). Live stock feeds and feeding.Agricultural and Food Research Council .Nutrition Abstract and Review, Series B,61: 683 – 722.BATEMAN, G. (1998). Environmental impact ofpollutants from pig farming and currentlegislative developments. Pages 251 –268. In: WISEMAN, J., VARLEY, M. A. andCHADRWICK, J. P. (Ed). Progress in PigScience. Nottingham University Press.Nottingham.BEERS, S. and JONGBLOED, A. W. (1992).Apparent overall (total) digestibility ofphosphorus in relation to doses ofAspergillus niger phytase in diets for pigs.Journal o f Animal Science, 70: 237 – 242.BEAL, J. D., BROOKS, P. H. and SCHOLETZE, H.(1998). The effect of pre-treatment withdifferent proteases on the in-vitrodigestibility of nitrogen in raw soyabeanand four different processed full fatsoybean meals. Pages 112 -115. In: VANARENDONK, J. A. M. DUCROCQ, V., VANDER HONING, Y., MADEC, F., VAN DERLENDE, T., PULLER, D., FOLCH, J.,FERNANDEZ, E. W. and BRUNS, E.W.(ED). Book of Abstract of the 49 th meetingof the European Association of AnimalProduction. Warsaw 24 th – 29 th August,1998.BLANDER, R, J. and FLEGAL, C. (1996). The effectof using phosphate enzyme on theperformance of growing market Turkeys