P. W. Plumstead

Interaction of Calcium and Phytate in Broiler Diets. 1. Effects on Apparent Prececal Digestibility and Retention of Phosphorus

Phytate P utilization from soybean meal (SBM) included in broiler diets has been shown to be poor and highly dependent on dietary Ca intake. However, the effect of Ca on P utilization and on the optimal ratio of Ca to nonphytate P (Ca:NPP) when diets contained varying levels of phytate has not been clearly shown and was the objective of this research. A factorial treatment structure was used with 4 dietary Ca levels from 0.47 to 1.16% and 3 levels of phytate P (0.28, 0.24, and 0.10%). Varying dietary phytate P levels were obtained by utilizing SBM produced from 3 varieties of soybeans with different phytate P concentrations. Ross 508 broiler chicks were fed 1 of 12 diets from 16 to 21 d of age. Excreta were collected from 16 to 17 d and from 19 to 20 d of age and ileal digesta was collected at 21 d of age. Apparent prececal P digestibility decreased when dietary Ca concentration increased and was higher when diets contained low-phytate SBM. The apparent digestibility of Ca and percentage of phytate P hydrolysis at the distal ileum were not reduced when dietary phytate P concentration increased. Including low-phytate SBM in diets reduced total P output in the excreta by 49% compared with conventional SBM. The optimum ratio of Ca:NPP that resulted in the highest P retention and lowest P excretion was 2.53:1, 2.40:1, and 2.34:1 for diets with 0.28, 0.24, and 0.10% phytate P. These data suggested that increased dietary Ca reduced the extent of phytate P hydrolysis and P digestibility and that the optimum Ca:NPP ratio at which P retention was maximized was reduced when diets contained less phytate P.

The effects of oviposition time on egg weight loss during storage and incubation, fertility, and hatchability of broiler hatching eggs

An experiment was conducted to determine the effect of time of oviposition, generally representing different positions in the normal egg laying sequence, on egg weight loss during storage and incubation, and on fertility and fertile hatchability of eggs from mid-lay (42 wk) and old (67 wk) broiler breeders. A total of 1,800 eggs (900 eggs per flock age) were collected during 10 consecutive days between 0830 and 1830 h each day. The eggs were individually marked, weighed, and stored for 1 to 10 d before incubation was initiated. Egg weight remained less from collection through incubation for eggs from the mid-lay flock than those from the old flock. Fresh weight of early laid (first-in-sequence; C1) eggs was significantly greater than that for the middle-of-day laid (mid-sequence; Cs), or late-in-day laid eggs (terminal-in-sequence; Ct). Percentage of egg weight loss during storage did not differ significantly between the mid-lay and old flocks but percentage of weight loss in the mid-lay flock was greater during incubation. Egg weight loss during storage of eggs from the middle-of-day laid (Cs) eggs was significantly greater than for early laid (C1) eggs, which was greater than for the late-in-day laid (Ct) eggs. Fertility was significantly decreased due to flock age but not due to oviposition time. Fertile hatchability was also significantly decreased due to flock age, but there was no significant effect of oviposition time. Early and late dead embryos increased with flock age, but there was no significant effect of oviposition time. It was concluded that there was no effect of oviposition time on fertility or fertile hatchability even though there were significant differences in egg weight and egg weight loss during storage due to oviposition time.

Broiler incubation. 2. Interaction of incubation and brooding temperatures on broiler chick feed consumption and growth

The effect of either hot or cool brooding litter temperature on feed consumption, BW, and mortality of broiler chicks that had been exposed to either normal or high temperature during latter stages of incubation was studied in 2 experiments. The duration of experiments 1 and 2 was 14 and 21 d, respectively, with BW and feed consumption determined at 2, 5, 7, and 14 d of age in experiment 1 and at 7, 14, and 21 d of age in experiment 2. High incubator temperature after embryonic d 16 decreased chick feed consumption and BW at all ages in both experiments. Hot brooding litter temperature increased feed consumption at 2 and 5 d in experiment 1 and at 7 d in experiment 2 but decreased feed consumption at 14 and 21 d in experiment 2. Feed consumption was also influenced by the incubation temperature x brooding litter temperature interaction. From 0 to 2 d or 0 to 7 d in experiments 1 and 2, respectively, the highest to lowest feed consumption was exhibited by the normal-hot, high-hot, normal-cool, and high-cool interaction groups but the order changed to normal-cool, normal-hot approximately high-cool, and high-hot from 7 to 14 and 14 to 21 d in experiment 2. Significant effects on mortality were observed in experiment 2 only where males exhibited greater mortality that was most evident in the combination of high temperature incubation followed by cool brooding. Excessive (high) eggshell temperature during the latter stages of incubation reduced feed consumption and BW through 21 d of age. However, the results showed that the hot brooding litter temperature supported increased feed consumption during the first few days of brooding even for the chicks that had been subjected to high incubation temperature. Hot brooding also reduced male mortality in experiment 2. Nonetheless, hot brooding litter temperatures should be limited as extending beyond a few days eventually decreased feed consumption.

Evaluation of phosphorus characterization in broiler ileal digesta, manure, and litter samples: (31)P-NMR vs. HPLC.

Using 31-phosphorus nuclear magnetic resonance spectroscopy ((31)P-NMR) to characterize phosphorus (P) in animal manures and litter has become a popular technique in the area of nutrient management. To date, there has been no published work evaluating P quantification in manure/litter samples with (31)P-NMR compared to other accepted methods such as high performance liquid chromatography (HPLC). To evaluate the use of (31)P-NMR to quantify myo-inositol hexakisphosphate (phytate) in ileal digesta, manure, and litter from broilers, we compared results obtained from both (31)P-NMR and a more traditional HPLC method. The quantification of phytate in all samples was very consistent between the two methods, with linear regressions having slopes ranging from 0.94 to 1.07 and r(2) values of 0.84 to 0.98. We compared the concentration of total monoester P determined with (31)P-NMR with the total inositol P content determined with HPLC and found a strong linear relationship between the two measurements having slopes ranging from 0.91 to 1.08 and r(2) values of 0.73 to 0.95. This suggests that (31)P-NMR is a very reliable method for quantifying P compounds in manure/litter samples.

Feeding Broiler Breeder Males. 4. Deficient Feed Allocation Reduces Fertility and Broiler Progeny Body Weight

Two experiments were conducted to evaluate the effects of male broiler breeder feed intake on broiler progeny performance. In experiment 1, a low cumulative nutrition program supplied 29,580 kcal of ME and 1,470 g of CP, whereas a high cumulative nutrition program supplied 33,500 kcal of ME and 1,730 g of CP to photostimulation at 21 wk of age. Two diets (HiDiet and LoDiet) were formulated, and a single feeding program was used to achieve the selected nutrient intakes. The HiDiet group of males in experiment 1 achieved greater BW and exhibited lower fertility when fed as the LoDiet males from the onset of egg production. The HiDiet breeder males subsequently produced male broilers from eggs laid at 29 wk of age that exhibited lower BW at 42 d. This was due to the heaviest 50% of the breeder males in this treatment not gaining BW consistently due to less-than-adequate ME intake relative to their greater BW requirements. Two feeding programs during the production period (constant or increasing) were compared in experiment 2. Broilers were hatched from eggs laid at 32 and 48 wk of age to evaluate the vertical effect of male treatments on progeny performance. No difference in fertility or broiler performance was found at 32 wk. However, the constant feeding program produced lower fertility from 36 to 55 wk of age, and this resulted in a lower male and female broiler progeny BW at 42 d of age from eggs collected at 48 wk of age. Adequate breeder male feed allocation during the production period improved fertility and favorably affected broiler progeny performance in both experiments. However, broiler progeny effects were observed only when there were differences in fertility, which suggests that the males with the greatest genetic potential were not mating at these times.

Interaction of Calcium and Phytate in Broiler Diets. 2. Effects on Total and Soluble Phosphorus Excretion

Dietary Ca has been reported to influence the amount of phytate excreted from broilers and affect the solubility of P in excreta. To address the effects of dietary Ca and phytate on P excretion, 12 dietary treatments were fed to broilers from 16 to 21 d of age. Treatments consisted of 3 levels of phytate P (0.10, 0.24, and 0.28%) and 4 levels of Ca (0.47, 0.70, 0.93, and 1.16%) in a randomized complete block design. Feed phytate concentrations were varied by formulating diets with 3 different soybean meals (SBM): a low-phytate SBM, a commercial SBM, and a high phytate Prolina SBM having phytate P concentrations of 0.15 to 0.51%. Fresh excreta was collected from cages during 2 separate 24-h periods; collection I commenced after the start of dietary treatments (16 to 17 d) and collection II followed a 3-d adaptation period (19 to 20 d). Ileal samples were also collected at 21 d. Excreta samples were analyzed for total P, water soluble P (WSP), and phytate P, whereas ileal samples were analyzed for total P and phytate P. Results indicated that excreta total P could be reduced by up to 63% and WSP by up to 66% with dietary inclusion of low-phytate SBM. There was a significant effect of dietary Ca on both the excreta WSP and the ratio of WSP:total P. As dietary Ca increased, the excreta WSP and WSP:total P decreased, with the effects being more pronounced following a dietary adaptation period. There was a linear relationship between the slope of the response in WSP to dietary Ca and feed phytate content for excreta from collection II (r(2) = 0.99). There was also a negative correlation between excreta phytate concentration and excreta WSP during both excreta collections. The response in WSP to dietary manipulation was important from an environmental perspective because WSP in excreta has been related to potential for off-site P losses following land application.