The use of enzymes in poultry diets
Despite their widespread use in poultry diets, the ways in which enzymes function are still not fully understood. Whilst it is agreed that a reduction of intestinal viscosity is the most likely mechanism when the appropriate enzymes are used in barley- and rye-based diets, some animal nutritionists claim that this is not so important in enzyme supplemented wheat-based diets. This paper, which attempts to place the relevant pieces of information into context, indicates that, even in the case of wheat-based diets, intestinal viscosity is a major factor limiting bird performance. Thus, in wheat fed birds the use of enzymes to reduce intestinal viscosity is likely to be the most effective method for improving performance. Data are also presented which, contrary to popular belief, indicate that most of the beneficial effects resulting from the feeding of xylanase-based enzymes to broilers are observed in the latter stages of the production cycle. 
Evaluation of Amino Acid and Energy Utilization in Feedstuff for Swine and Poultry Diets
An accurate feed formulation is essential for optimizing feed efficiency and minimizing feed cost for swine and poultry production. Because energy and amino acid (AA) account for the major cost of swine and poultry diets, a precise determination of the availability of energy and AA in feedstuffs is essential for accurate diet formulations. Therefore, the methodology for determining the availability of energy and AA should be carefully selected. The total collection and index methods are 2 major procedures for estimating the availability of energy and AA in feedstuffs for swine and poultry diets. The total collection method is based on the laborious production of quantitative records of feed intake and output, whereas the index method can avoid the laborious work, but greatly relies on accurate chemical analysis of index compound. The direct method, in which the test feedstuff in a diet is the sole source of the component of interest, is widely used to determine the digestibility of nutritional components in feedstuffs. In some cases, however, it may be necessary to formulate a basal diet and a test diet in which a portion of the basal diet is replaced by the feed ingredient to be tested because of poor palatability and low level of the interested component in the test ingredients. For the digestibility of AA, due to the confounding effect on AA composition of protein in feces by microorganisms in the hind gut, ileal digestibility rather than fecal digestibility has been preferred as the reliable method for estimating AA digestibility. Depending on the contribution of ileal endogenous AA losses in the ileal digestibility calculation, ileal digestibility estimates can be expressed as apparent, standardized, and true ileal digestibility, and are usually determined using the ileal cannulation method for pigs and the slaughter method for poultry. Among these digestibility estimates, the standardized ileal AA digestibility that corrects apparent ileal digestibility for basal endogenous AA losses, provides appropriate information for the formulation of swine and poultry diets. The total quantity of energy in feedstuffs can be partitioned into different components including gross energy (GE), digestible energy (DE), metabolizable energy (ME), and net energy based on the consideration of sequential energy losses during digestion and metabolism from GE in feeds. For swine, the total collection method is suggested for determining DE and ME in feedstuffs whereas for poultry the classical ME assay and the precision-fed method are applicable. Further investigation for the utilization of ME may be conducted by measuring either heat production or energy retention using indirect calorimetry or comparative slaughter method, respectively. This review provides information on the methodology used to determine accurate estimates of AA and energy availability for formulating swine and poultry diets. 
Heat stress and dietary vitamin supplementation of poultry diets
A seasonal problem in many parts of the world, a high ambient temperature causes economic losses through reducing feed intake while decreasing nutrient utilization, live weight gain, egg production, egg quality and feed efficiency of poultry. Several methods are currently available to alleviate the negative effects of high environmental temperature on the performance of poultry. However, since it is expensive to cool buildings in which animals are housed, such methods are focused mostly on dietary manipulation. In terms of reducing the negative effects of environmental stress, vitamin C, vitamin E and vitamin A are used in the poultry diet because of the reported benefits of these vitamins including their anti-stress effects and also due to the fact that their utilization and thus normal concentrations are reduced during heat stress. This review focuses on the effects of dietary vitamin (C, E and A) supplementation in poultry reared under chronic heat stress.
Effect of Dietary Inclusion of Rice Husk Supplemented with Commercial Enzymes on Performance, Nutrient Retention and Gastro-intestinal Tract Characteristics of Arbor Acres Broilers
Aims: This experiment was carried out to assess the effect of dietary inclusion of rice husk supplemented with commercial enzyme on performance, nutrient retention and gastro-intestinal tract characteristics of chicken broilers. The experimental design was a 2×4 factorial combination of two dietary level of rice husk (0 or 25%) with four levels of different commercial enzymes 0E (without enzyme 0ppm), 100E (100ppm of Phytase), 150E (150 ppm of Nutrase xyla), or 350E (350ppm of Grindazyme). Rice husk was added at the expense of maize in the control diet, and each experimental diet was tested during a 56-day feeding trial in triplicate. One hundred and ninety-two (192) one-day old unsexed Arbor acres chicks were used in the trial. Experimental diets and water were supplied ad-libitum to the birds from day the first day to day 56 and chicks were subjected to the recommended routine vaccination programmed. A nutrient digestibility trial was undertaken when the birds were 3 weeks old. At the end of the feeding trial, 3 birds per replicate were randomly selected, euthanatized by neck decapitation, then eviscerated, and the crop, proventriculus, gizzard, liver and pancreas weights were determined. The results showed that an increase in the dietary level of rice husk without commercial enzyme supplementation significantly decreased (P<0.05) weight gain, feed conversion ratio and nutrient digestibility. There were significant (P<0.05) interactions between dietary levels of rice husk and the inclusion of commercial enzymes on performance, nutrient digestibility and gastro-intestinal tract characteristics of chicks. Hypertrophy of the digestive organs was observed in birds fed rice husk without enzyme supplementation. However, this effect was attenuated with the inclusion of commercial enzymes. Results obtained showed that birds fed rice husk diets supplemented with commercial enzymes performed better in all parameters tested than those fed rice husk diets without commercial enzyme. The use of commercial enzyme is advantageous in the utilization of high-fibre diets for chicks. The dietary supplementation with commercial enzymes increased the weight gain, feed conversion ratio and improved nutrient digestibility in broilers, which supposes a beneficial reduction in the production costs 
Performance of Broiler Chickens Fed Graded Dietary Levels of Rice Milling Residue as a Fibre Source
An experiment was conducted to evaluate the growth performance of broilers fed dietary levels of rice milling residue (RMR) as a replacement of wheat offal (WO), as a fibre source in broiler diet. Three hundred (300) day old chicks were used for the experiment in a completely randomized design (CRD) for eight (8) weeks. The birds were randomly allotted to five (5) dietary treatments of sixty (60) chicks and replicated three (3) times with twenty (20) chicks per replicate. Five (5) treatment diets were formulated in which rice milling residue (RMR) was included to replace wheat offal (WO) at the levels of 0, 25, 50, 75 and 100% representing T1, T2, T3, T4 and T5 respectively. The result of the growth performance showed that, the average daily feed intake (ADFI), average daily weight gained (ADWG) were not significantly different (P>0.05) across treatment groups except feed conversion ratio (FCR). Birds fed T1, T2, T3 and T5 recorded Superior FCR. ADWG ranged from 31.31 g (T1) to 32.82 (T3). Birds on T3 diet recorded higher feed intake of 130.15 g while the least was observed in T1 (116.82 g). It was concluded that rice milling residue (RMR) can completely replace wheat offal without any detrimental effect on growth performance of broilers chickens. 
 Bedford, M.R. and Morgan, A.J., 1996. The use of enzymes in poultry diets. World’s Poultry Science Journal, 52(1), pp.61-68.
 Kong, C. and Adeola, O., 2014. Evaluation of amino acid and energy utilization in feedstuff for swine and poultry diets. Asian-Australasian Journal of Animal Sciences, 27(7), p.917.
 Sahin, K. and Kucuk, O., 2003. Heat stress and dietary vitamin supplementation of poultry diets. In Nutrition Abstracts and Reviews. Series B, Livestock Feeds and Feeding (Vol. 73, No. 7). CAB International.
 Alabi, O.O., Atteh, J.O. and Ogunniyi, P.T., 2014. Effect of Dietary Inclusion of Rice Husk Supplemented with Commercial Enzymes on Performance, Nutrient Retention and Gastro-intestinal Tract Characteristics of Arbor Acres Broilers. Journal of Experimental Agriculture International, pp.575-583.
 Olusiyi, J.A. and Wafar, R.J., 2017. Performance of Broiler Chickens Fed Graded Dietary Levels of Rice Milling Residue as a Fibre Source. Asian Research Journal of Agriculture, pp.1-6.
The use of enzymes in poultry diets