Biological value of bone-precipitated dicalcium phosphate in turkey starter diets.

A study was conducted to determine the relative biological value (RBV) of phosphorus from two bone-precipitated dicalcium phosphates (DCP-BP) in turkey starter diets. An estimated 40,000 metric tons of DCP-BP are produced annually in the United States as a by-product of gelatin production. The two DCP-BP sources were compared to commercial feed phosphates. Two bioassay experiments of 21-d duration were conducted with female turkeys. Phosphate sources were each fed at three levels (.18, .24, and .36% added total phosphorus) in a corn-soybean meal diet. Calcium level was maintained constant at 1.0% in all diets by adjusting the level of ground limestone. Four replicate pens of six poults were randomly assigned at 1 d of age to each level of each phosphorus source in each bioassay. The reference standard was United States Pharmacopeia (USP) grade calcium phosphate, dibasic dihydrate. Data representing three response criteria (weight gain, gain:feed ratio, and tibia ash percentage at 21 d) were combined to calculate a biological value (BV) for each test source and the reference standard phosphate. A RBV was then computed for each test source. The RBV of the two DCP-BP sources were 98.8 and 99.1, as compared to 100.0 for the reference standard, and 86.7, 87.1, and 88.4 for three commercial, thermochemically produced defluorinated phosphates. The RBV of one commercial mono-dicalcium phosphate, and three di-monocalcium phosphates were: 96.4, and 91.2, 94.7, and 101.5, respectively. The two DCP-BP sources compared favorably to commercial feed phosphates, and would be satisfactory supplements in diets for starting chicks, poults, pigs, and other species.

Stress measurements on beak-trimmed and untrimmed pullets.

Stress in poultry is difficult to define and measure. There is general agreement that some modern poultry production practices may exert a certain amount of stress on birds. Three experiments were conducted to explore possible measures of stress associated with beak trimming and rearing schemes. Experiments 1 and 2 examined different degrees of beak trimming and rearing schemes of wire floor versus litter floor in pullet production. Experiment 3 examined the effect of beak trimming on feed consumption for 14 days after trimming. Adrenal glands of untrimmed birds were heavier (P less than .05) than those of trimmed birds at the end of the pullet growing period in Experiments 1 and 2, evidence that beak trimming reduced overall chronic stress levels. Hearts of untrimmed birds were heavier (P less than .05) than those of trimmed birds in Experiment 1. Hearts and spleens were not affected in Experiment 2. In comparisons of rearing schemes (litter versus wire), birds grown on litter floors had heavier adrenal glands and a greater incidence of cannibalism in the later weeks of Experiments 1 and 2. This indicated that a stressful interaction among penmates had occurred. Birds grown on litter floors consumed more feed than those grown on wire, and the untrimmed birds from both floor types consumed more total feed than trimmed birds. By the end of the growing period, body weights were not different in either study, indicating compensation for any early beak trimming stress. Beak trimming produced a decrease in feed intake in Experiment 3, consumption was reduced (P less than .05) in 5 of the first 8 days after trimming.

Effect of rearing floor type and ten-day beak trimming on stress and performance of caged layers.

Beak trimming pullets at an early age is a widespread industry practice. There is some concern that this practice may have effects on the subsequent performance of the birds in the production phase. Effects of beak treatment (trimmed or untrimmed) and rearing floor type (litter or wire) on performance of caged layers were evaluated in a 2 x 2 factorial arrangement of treatments. Pullets that were trimmed or untrimmed at 10 days of age and reared on either litter or wire floors were placed in a cage house. Production factors and stress measurements were recorded to determine detrimental effects of the early trimming and rearing floor types. No interactions (P = .15) between rearing floor type and beak treatment were observed for BW, feed consumption, egg production, heart weight, spleen weight, or blood corticosterone. However, an interaction (P = .02) between rearing floor type and beak treatment was observed for adrenal weight. There were no differences (P = .08) in the final BW of the pullets. Birds reared on litter ate considerably (P = .0002) more than those reared on wire. There were no differences (P = .27) in egg production rate. Adrenal weights were different (P = .007), with the litter-raised birds having much smaller adrenals at the end of the 36-wk trial. Hearts of the beak-trimmed birds were smaller (P = .02) than those of the untrimmed birds. There were no differences in spleen weights (P = .07) or blood corticosterone levels (P = .07). Differences in the feather cover were observed.