A 4 x 2 factorial experiment with 4 dietary energy levels (2,719, 2,798, 2,877, and 2,959 kcal of ME/ kg) and 2 strains (Bovans White and Dekalb White) was conducted to determine the effect of dietary energy on reproductive performance, egg composition, and profits of 2 strains of commercial Leghorns. This experiment lasted 16 wk. Bovans White hens (n = 768) and Dekalb White hens (n = 768) in phase I (21 wk of age) were randomly assigned into 8 treatments (16 replicates of 12 birds/treatment). Bovans White had significantly higher feed intake, egg production, egg mass, body weight, percentage egg yolk, and yolk/albumen ratio than Dekalb White. Bovans White had significantly lower feed conversion, egg weight, egg specific gravity, percentage of albumen weight, percentage of shell weight, and Haugh unit than Dekalb White. When dietary energy increased from 2,719 to 2,956 kcal of ME/kg, hens adjusted feed intake from 107.6 to 101.1 g/hen per day to achieve a constant energy intake so that the same amount of dietary energy (5.8 kcal) was used to produce 1 g of egg. Increasing dietary energy by the addition of poultry oil increased early egg weight, which was mostly due to increased yolk weight. Increasing dietary energy by addition of poultry oil significantly decreased feed conversion and egg specific gravity but had no effect on egg production, egg mass, body weight, or mortality. Increasing dietary energy by addition of poultry oil to a ratio of 282 kcal of ME/g lysine maximized egg weight during phase I. The energy per lysine ratio required for optimal profits varied with egg price and feed ingredient prices, which were variable.

beta-Mannanase (Hemicell) is a unique enzyme-based feed ingredient that can hydrolyze beta-mannan, an antinutritional fiber in feed. Because soybean meal contains beta-mannan and its derivatives, addition of beta-mannanase may improve soybean-meal utilization. The purpose of this study was to evaluate the effect of beta-mannanase on performance of commercial Leghorns fed corn-soybean meal based diets. In this experiment, 3 diets were formulated. The metabolizable energy content for diet 1 (high-energy diet) was 2,951 kcal/kg, which was 120 kcal/kg higher than diet 2 (low-energy diet supplemented with beta-mannanase) and diet 3 (low-energy diet without beta-mannanase). Hy-Line W-36 hens (n = 720, 98 wk old) were randomly divided into 3 dietary treatments (16 replicates of 15 hens per treatment). The trial lasted for 12 wk. Overall average feed conversion of hens fed the low-energy diet supplemented with beta-mannanase was similar to that of hens fed the high-energy diet, and both were significantly lower than that of hens fed the low-energy diet without beta-mannanase. There were no significant differences in overall average egg production and egg mass among 3 dietary treatments for the 12-wk period. However, the addition of beta-mannanase significantly increased average egg production and egg mass of hens fed the low-energy diet from wk 5 to 8. There were no significant differences in feed intake, egg specific gravity, egg weight, mortality, body weight, and body weight variability among the 3 dietary treatments. beta-Mannanase supplementation improved energy utilization of corn-soybean layer diets and has potential to reduce the cost of practical laying hen diets containing beta-mannan.

Four experiments were conducted to determine the effect of light during incubation on embryonic and post-embryonic development of broiler chickens. The eggs were randomly assigned to one of three lighting regimes during the incubation period: (a) a diurnal light cycle consisting of a 12-hour light period followed by a 12-hour dark period (12L-12D), (b) 24 hours of light (24L-OD), and (c) 24 hours of darkness (0L-24D) per day.The development of the embryos was accelerated by increasing the length of exposure to light during incubation. There were no significant differences between treatments in initial body weights of those chicks that hatched early and those which required 21 days to hatch. Body weights of the chickens at four and eight weeks post-hatch showed no significant differences between treatment groups. Embryo weights at 12 and 18 days of incubation were heavier when increased amounts of light were provided during incubation. The incidence of healed navels was increased with greater length of exposure to light during incubation.From these data it was hypothesized that the rate of embryonic development, as measured by hours of incubation, navel score, embryo and chick weights, is accelerated by an exposure to light during incubation. There were no deleterious effects of exposure to light during incubation as measured by body weights at hatch, four weeks and eight weeks of age.

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Sixty Marston Broad White toms were used in each of two experiments (hatched February and late July) and were equally divided among six floor pens (1.5X2.4 m.). All birds were fed a commercial type starter diet through the tenth week of age. From the eleventh through the twenty-fourth week of age, one-half of the birds were fed a low protein grower diet (10.2 percent protein) while the remaining birds were fed the control grower (21 percent protein). Beginning with the twenty-fifth week all birds received a commercialtype breeder diet. At 30 weeks of age one male was placed in each of 18 female pens (ten females per pen).Body weights for the restricted males were 36-38 percent lighter than the controls at 24 weeks of age and changes in conformation were such that males fed the low protein grower diet could be ejaculated more easily than the controls. In general, the semen characteristics of the restricted males were also superior; however, this difference was non-significant. Fertility for the February hatched, naturally mated, birds was more than 100 percent higher for the males fed the low protein grower diet while fertile hatch was numerically, but not significantly, higher than the controls. Fertility and fertile hatch for the naturally mated, July hatch, birds were numerically, but not significantly, higher for the males fed the low protein grower diet. In the artificially inseminated birds, fertility and fertile hatch of the males fed the low protein grower diet were numerically, but not significantly, greater than the controls, in both experiments.It is obvious from these data that increased reproductive efficiency results from nutrient restriction of toms during the growing period.

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Two experiments were conducted utilizing a total of 720 Marston Broadwhite females (hatched late December and July). The day old poults were equally divided among 18 floor pens and fed a turkey starter (27.8% protein) from 0-10 weeks of age. Onethird of the birds was assigned to each of the following feeding regimes: control grower (21% protein ad libitum), low protein (10.2% protein ad libitum), or skip-a-day (75% of control grower). All birds remained on these treatments through 24 weeks of age when the control group was placed on a commercial-type breeder diet (16.6% protein); six weeks later the remaining treatment groups were changed to this diet.Feed consumption and body weights were consistently greater for the control group. In all cases, regardless of season of the year or whether the birds were cage or floor reared, the age at sexual maturity was significantly delayed for the restricted birds as compared to the controls.Subsequent egg production tended to be greater in the restricted groups even when the initial two 28-day periods (while the two restricted groups were still on treatment) were included. Egg weight was not affected by treatment; however, it should be noted that the control group laid a much larger number of eggs that were considered too small for setting.It was concluded that nutrient restriction during the growing period is a highly effective method of delaying sexual maturity in the turkey breeder hen and, in addition, reduces production costs. It is hypothesized that any reasonable method of nutrient restriction will be effective if the program is designed to bring a hen to sexual maturity at a specific weight and age.