W. Bolton

Digestion in the crop of the fowl

Synopsis Examination of the crop contents of fowls has shown that there is extensive hydrolysis of starch to sugar and that much of the sugar formed can be lost from the crop by absorption by the crop, the action of micro‐organisms or leaching from the crop. When crop contents were incubated anaerobically, lactic and acetic acids and alcohol were produced. Examination post‐mortem of crop contents from birds with “sour crops” indicated that, in addition to the formation of lactic and acetic acids, formic, propionic and butyric acids can also be formed.

The digestibility of acetic, propionic and butyric acids by the fowl

Synopsis Acetic, propionic and butyric acids, fed as the calcium salts at a level so that the diet contained about 2.5 per cent of the fatty acid ion, were completely digested. Examination of the contents of gut sections indicated that each acid was completely removed from the ingesta before this reached Meckels diverticulum.

Effects of food regulation during the growing and laying stages on the productivity of broiler breeders

1. From 1 to 22 weeks of age 720 Ross 1 parent stock pullets were given regulated amounts of food to achieve 90, 100 or 110% of a target weight (R90, R100 or R110, respectively) while from 23 to 64 weeks of age they were fed 80 or 100% of a set allowance (L80 or L100, respectively). One hundred and fifty Ross 1 parent stock males were on the R110 treatment and then either the L80 or L100 during breeding. 2. Mean number of settable (> 53 g) eggs per hen housed was 131, 131 and 135 and mean number of chicks hatched per hen housed was 108, 101 and 101, respectively, for the R90, R100 and R110 treatments. These differences were not statistically significant. 3. Mean number of settable eggs per hen housed was 116 and 148 and mean number of chicks hatched per hen housed was 94 and 112, respectively, for the L80 and L100 treatments (P<0.001). 4. Fertility and hatchability were improved but uniformity of the birds was decreased by restricting food intake.

The hen's egg: Genetics of taints in eggs from hens fed on rapeseed meal

1. Fishy taints in eggs from hens fed on rapeseed meal, which have been reported to occur in brown‐shelled eggs of some hens with Rhode Island Red ancestry, occur also in white‐shelled eggs of some hens of a strain of Brown Leghorns. 2. Genetic tests have demonstrated that tainting in these circumstances is conditional on the presence in the hen, in the heterozygous or homozygous state, of an autosomal semi‐dominant mutant gene that has variable expression, depending on environmental factors (including the rate of ingestion of rapeseed meal). 3. No simple test for the presence of this gene, applicable to either sex, can be anticipated at present.

Effect of stocking density on performance of broiler chicks.

Synopsis In two experiments space allowances of 0.143, 0.122, 0.105 and 0.093 m2/bird and 0.093, 0.078, 0.064 and 0.047 m2/bird were used and their effects on live‐weight, food consumption and food conversion of Cobb broilers up to 10 weeks old were measured. When the space allowance was greater than 0.093 m2/bird there was no effect on any of the characters studied. At 10 weeks old a decrease in space allowance from 0.093 to 0.047 m2/bird was accompanied by reduced final live‐weight and food consumption and increased efficiency of food conversion; the effect on live‐weight was smaller at 9 weeks and was not significant at 8 or 7 weeks. It was concluded that in broiler experiments ending at 8 weeks a space allowance of 0.078 m2/bird (0.8 ft2/bird) is more than adequate.

Growth of broilers given diets containing field beans (vicia faba l.) during period the 0 to 4 week

Synopsis In the first experiment 32 groups, each of about 30 male or female Ross 1 chicks, were given mash diets containing 0, 15, 30 or 45 per cent field beans from one day of age for 4 weeks. From 4 to 8 weeks they were given pelleted diets containing 30 or 45 per cent field beans, the treatments being imposed in a 2 (sexes) x 4x2 factorial design. Increasing the proportion of beans in the diet gave a significant worsening in food conversion ratio and in live‐weight gain to 4 and 8 weeks. In the second experiment 30 groups, each of about 32 male Ross 1 chicks, were given diets containing o, 30, 45, 30 or 45 per cent beans from one day of age to 4 weeks. In the second and third diets the digestibility of bean protein was assumed to be 100 per cent; in the fourth and fifth diets the digestibility was assumed to be 80 per cent and higher concentrations of other protein supplements were therefore included. All diets were prepared as mash, pellets and ground pellets. From 4 to 8 weeks all groups were given a...

Growth of broilers given diets containing field beans (Vicia faba L.) during the 0 to 4 week period.

Synopsis In the first experiment 32 groups, each of about 30 male or female Ross 1 chicks, were given mash diets containing 0, 15, 30 or 45 per cent field beans from one day of age for 4 weeks. From 4 to 8 weeks they were given pelleted diets containing 30 or 45 per cent field beans, the treatments being imposed in a 2 (sexes) x 4x2 factorial design. Increasing the proportion of beans in the diet gave a significant worsening in food conversion ratio and in live‐weight gain to 4 and 8 weeks. In the second experiment 30 groups, each of about 32 male Ross 1 chicks, were given diets containing o, 30, 45, 30 or 45 per cent beans from one day of age to 4 weeks. In the second and third diets the digestibility of bean protein was assumed to be 100 per cent; in the fourth and fifth diets the digestibility was assumed to be 80 per cent and higher concentrations of other protein supplements were therefore included. All diets were prepared as mash, pellets and ground pellets. From 4 to 8 weeks all groups were given a...

Battery gage shape: The laying performance of medium‐ and light‐body weight strains of hens

1. One thousand two hundred and ninety‐six medium‐ and 1296 lightweight hens were housed, four to a cage, in deep (conventional) cages, 405 mm wide by 460 mm deep, or shallow cages, 610 mm wide by 305 mm deep, between 18 and 70 weeks of age. The performance of the hens during different periods of the laying stage and over the full laying year was measured. 2. Egg number per medium‐weight hen housed in shallow cages was significantly higher than of hens housed in deep cages between 18 and 30 weeks and 31 and 42 weeks. Thereafter significant differences were not found. With the light‐weight hens the increase was significant only in the 18‐ to 30‐week period. Apart from the 19‐ to 30‐week period hens of both strains housed in shallow cages consumed significantly less food than those in deep cages, the reduction over the full year being about 4%. In all periods the hens housed in the shallow cages converted food more efficiently. Gage shape had no significant effect on mortality. 3. The incidence of hair‐crac...

Egg production of light and medium hybrids given diets varying in protein level during the rearing and laying stages

Synopsis From 6 to 16 weeks of age Sterling White Links and Sterling Ranger IIs were given one of four diets containing 0 or 5.1 per cent meat‐and‐bone meal and 5.1 or 10.2 per cent soyabean meal. During the laying stage they were given one of two diets containing 14 per cent protein (meeting the Agricultural Research Councils (1963) estimated amino acid requirements as closely as possible) or 16.0 per cent protein. Reducing the level of protein in the rearing diet led to a significant (P < 0.001) reduction in live‐weight at 16 weeks and to a significant decrease in mean egg weight (P < 0.05), but age at onset of lay and egg number and total weight of eggs were not significantly influenced. Increasing the level of protein in the laying diet did not significantly influence the number of eggs laid but led to a significant (P < 0.001) increase in mean egg weight. At all stages the medium hybrids were heavier than the light hybrids; in addition they laid fewer but larger eggs and their food conversion effic...

Effect of age of the laying hen on the composition of the egg

abstract 1. All eggs laid by a group of 16 light‐body‐weight hens during the laying year were weighed and divided into yolk, albumen and shell and the wet and dry weights of the components determined. 2. After an initial period of about 2 months, the weights of egg, water, wet albumen, wet and dry yolk increased with age, whereas those of dry albumen and wet and dry shell remained constant. Dry shell per square centimetre surface area decreased with age but water per square centimetre surface area remained constant.