J. M. McNab

The effect of heat treatment and enzyme supplementation on the nutritive value of barley for broiler chicks

1. The effect of heat treatment and enzyme supplementation on the nutritive value of barley was studied. 2. In only one experiment was weight gain significantly improved when the barley was heated. 3. Autoclaving barley at 120 °C for 30 min reduced dietary dry matter digestibility and treating the barley with dilute acid before heating had no effect on its nutritive value. 4. Supplementing diets containing commercial barley with a‐amylase produced slightly conflicting results in that there was an improved weight gain, food conversion efficiency and digestibility value in two of three experiments. 5. The digestibility and metabolisable energy values of a North American six‐row spring barley (Glacier) were significantly improved by enzyme supplementation. 6. The effect of the enzyme on diets containing a high amylose barley (Glacier Pentlandfield) was positive but not significant.

The nutritive value of barley, maize, oats and wheat for poultry

Synopsis The crude compositions of samples of barley, maize, oats and wheat are given together with a more detailed analysis of the protein and carbohydrate fractions. The nutritional potential of these samples to the laying hen has been investigated using colostomised birds. By regression analysis of absorption on intake, the true digestibility of the crude protein was calculated to be 83.6, 82.2, 85.0 and 847%, that of the crude fat 92.5, 94.9, 95.0 and 92.5% and that of the carbohydrate 73.0, 87.2, 52.1 and 81.1% for barley, maize, oats and wheat respectively. The true digestibility coefficients of some amino acids are also given. The classical meta‐bolisable energy values of the barley, maize, oat and wheat samples studied were found to be 11.12, 13.21, 11.05 and 12.18 MJ/kg (2.66, 3.16, 2.64 and 2.91 kcal/g) respectively. It is concluded that there is scope for improving the digestibility of the protein in all the cereals studied and that digestibility of the non‐starch carbohydrate fraction is very low.

The nutritive value of triticale and rye for the laying hen

1. The crude compositions of samples of triticale and rye are given together with more detailed analyses for the protein and carbohydrate fractions. 2. By regression analysis of absorption on intake, the true digestibilities of the crude protein, using colostomised birds, were calculated to be 85.2 and 72.0%, those of the crude fat 94.4 and 89.7% and those of the carbohydrate 82.0 and 75.5% for triticale and rye respectively. 3. The classical metabolisable energy values of the triticale and rye samples were found to be 14.08 and 12.51 MJ/kg (3.36 and 2.99 Mcal/kg) respectively. 4. It is concluded that triticale is a better food source for the chicken than either wheat or rye.

The effect of autoclaving and methionine supplementation on the growth of chicks given diets containing field beans (Vicia faba L.).

Synopsis Three experiments are described. The first two show that a beneficial effect on live‐weight gain and food conversion efficiency may be obtained when beans are autoclaved before feeding to chicks at levels up to 75% of the diet. However, much of the response obtained may have been due to an increase in amino acid availability after autoclaving. When no amino acids were limiting, the response in live‐weight gain to autoclaving was small and it is unlikely to justify commercial adoption. In the third experiment it was found that the gain was similar whether the beans were autoclaved for 15, 30, 60 or 90 min. No response to the removal of tannins by ethanol extraction was obtained.

The effect of different dietary levels of a n‐paraffin‐grown yeast on the growth and food intake of broiler chicks

Synopsis Sixteen groups, each of about 30 male or female Ross 1 chicks, were given pelleted diets containing 0, 5, 10 or 20% yeast in place of herring meal. The diets were given from 1 d of age for 4 weeks; from 4 to 8 weeks the birds were given a common broiler finisher diet. Replacing up to 10% herring meal by yeast did not significantly affect live‐weight at 4 weeks of age but food conversion efficiency was poorer with the diet containing 10% yeast. Birds given the diet containing 5% yeast to 4 weeks of age were significantly heavier at 8 weeks. The diet with 20% yeast significantly depressed growth at 4 and 8 weeks of age. The use of yeast in broiler finisher diets was investigated in a second experiment. Birds similar to those used in the first experiment were given diets containing yeast at levels of 0, 5, 10 or 20% from 4 to 8 weeks of age. Live‐weight at 8 weeks was not significantly affected by level of yeast in the diet; food conversion efficiency was significantly better with the 20% yeast diet...

Effects on chick growth of adding glycine, proline, glutamic acid or diammonium citrate to diets containing crystalline essential amino acids

Synopsis Purified diets, designed to supply a balanced sufficiency but not excess of essential amino acids, were supplemented with glycine, glutamic acid, proline or diammonium citrate (DAC) and fed to broiler chicks from the 7 d stage. Slow growth was obtained unless the diet was supplemented with 1 % L‐proline, confirming other work which suggests that proline should be reclassified as an essential amino acid for the chick. Increasing the level of glycine in the diet from 1 ‐o to 1 ‐6% did not result in a marked growth response. Adding 11–07% DAC to the diet gave a significant growth response and a significant increase in the plasma level of amino acids. The utilisation of DAC was equivalent to that of an isonitrogenous supplement of glutamic acid in one experiment, but was significantly poorer than that of glutamic acid in another. A significant linear regression of live‐weight gain on nitrogen intake was derived (r = 0–8582): growth was better on a practical than on any of the purified diets used but ...

Studies on the process of digestion in the fowl: Dry matter and total nitrogen

Synopsis Four pelleted diets, based on soybean meal (N = 4.40%), fish meal (N = 2.41%), field bean (Vicia faba L.) meal (N = 2.05%) and maize dextrin (N = 0.10%), were each offered to sixteen 13‐week‐old pullets for a 2 h period. Four birds from each group were killed 2, 4, 6 and 8 h after the feeding period and samples of the ingesta were removed from the gastro‐intestinal tract. The same experimental procedure, using the soybean meal diet, was also applied to sixteen 17‐week‐old and sixteen 24‐week‐old pullets. Nitrogen and chromium sesquioxide were determined on the freeze‐dried ingesta removed from the crops, proventriculi and gizzards, duodena, jejuna, ilea, caeca and large intestines of all the groups. The results indicated that the crop, proventriculus and gizzard acted as food reservoirs, that passage of food through the duodenum was very rapid and that the amount of the ingesta in the caeca depended on the diet, and was possibly affected by the nature of the carbohydrate. The rate and mode of dig...

The nutritive value of triticale and rye in broiler diets containing field beans (Vicia faba L.)

1. Diets containing wheat and maize (control), 300 g or 500 g triticale per kg or 300 g rye per kg were fed to broiler chickens for 56 d. 2. Live‐weight at 56 d of age was not different on a diet containing 300 g triticale per kg to that on the control diet but was significantly reduced by diets containing 500 g triticale or 300 g rye per kg. 3. Food conversion efficiency was best with 300 g triticale per kg of diet.

Enzyme studies with the livers of chicks fed semi-synthetic diets containing crystalline amino acids and diammonium citrate.

Synopsis The levels of glutamate dehydrogenase [NAD(P)], (GDH), aspartate trans‐aminase (AspT) and alanine transaminase (AlT) were measured in livers from chicks fed on a semi‐synthetic diet containing crystalline essential amino acids as the sole nitrogen source (diet A). The effects of a supplement of 12.0% glutamic acid (diet H) or 11.07% diammonium citrate (DAC) (diet B) or 12.0% glutamic acid plus 1.0% proline with an additional 0.6% glycine (diet C) on these enzymes were studied and the results compared with the levels found for control chicks given a typical diet based on cereal protein (diet J). The abilities of livers from chicks given diets A, B and C to synthesise [14C] glutamic acid from [14C]2‐oxoglutaric acid and diammonium citrate (DAC) were assessed. The levels of GDH, AspT and AlT found in the livers of chicks given the control diet were 54.1, 966 and 123.7 units/mg protein respectively. Non‐essential nitrogen added as glutamic acid or as DAC did not cause induction of the enzymes studied...

The effect on chick growth of a trypsin inhibitor isolate from the field bean (Vicia faba L.).

Synopsis An extract rich in trypsin‐inhibiting activity was obtained from field beans (Vicia faba L.) and added to a diet containing autoclaved field bean meal. There was no significant effect on chick growth but pancreas size was significantly increased and food conversion efficiency was reduced.