Two experiments were conducted to determine the effects of anticoccidial agents on production and reproduction of broiler breeders. In Experiment 1, nicarbazin (NCZ) was fed at 20, 50, and 100 ppm. There was no depression in egg production, egg weight, or fertility from feeding these levels. As level of NCZ increased, there was a linear decrease in hatchability. The amount of 4,4'-dinitrocarbanilide (DNC) in the egg yolks increased linearly as the levels of NCZ went up; the degree of egg-shell depigmentation was directly related to the level of NCZ fed starting at 50 ppm. Experiment 2 utilized a different strain of broiler breeders. Halofuginone (3 ppm), maduramicin (5 ppm), monensin (100 ppm), narasin (70 ppm), NCZ (125 ppm), robenidine (33 ppm), and salinomycin (60 ppm) were fed to broiler breeders at the levels listed. Only NCZ reduced egg production. Narasin induced a reduction in egg weight. Both narasin and salinomycin caused a significant drop in hatchability. Feeding NCZ also induced a rapid and more severe decrease in hatchability. Monensin was the only anticoccidial agent that reduced fertility. Halofuginone, maduramicin, and robenidine had no biologically significant effect on henday production, egg weight, hatch of fertile eggs, or shell depigmentation. Feeding NCZ at 125 ppm caused a complete bleaching of brown-shell eggs by the 3rd consecutive day of treatment; but 7 days after NCZ was withdrawn from the feed, pigmentation returned to the pretreatment level.

Two studies were conducted to determine the effects of anticoccidial agents on the production and reproduction of White Leghorns. In Experiment 1, nicarbazin (NCZ) was fed at 0, 20, 50, and 100 ppm. Hen-day egg production, egg weight, the egg-yolk DNC (4-4'-dinitrocarbanilide) level, and egg-yolk mottling were affected by the treatments. When response was evidenced, the relationship between those variables and the level of NCZ was basically linear. Decreased egg production occurred from Days 5 and 6 of the treatment through Days 1 and 2 of withdrawal. On Days 9 and 10 of treatment, the control hens peaked at 92% hen-day production, while hens fed 20, 50, and 100 ppm of NCZ peaked late--at 90, 82, and 80%, respectively. Compared to the controls, egg weight was reduced linearly as the level of dietary NCZ increased. The egg-yolk DNC level increased from Days 3 and 4 of treatment through Days 9 and 10 of withdrawal. Egg yolk mottling generally increased along with the level and duration of feeding NCZ. If the NCZ was mistakenly fed to White Leghorn layers, ill effects would be alleviated within 10 days after drug withdrawal. In Experiment 2, halofuginone (3 ppm), maduramicin (5 ppm), monensin (100 ppm), narasin (70 ppm), nicarbazin (125 ppm), robenidine (33 ppm), and salinomycin (60 ppm) were fed to White Leghorn hens at the levels specified in parentheses. Nicarbazin reduced egg production, depressed egg weight, reduced shell thickness, and caused egg-yolk mottling; but internal egg quality, as measured by Haugh Units, was unaffected. Halofuginone, maduramicin, monensin, narasin, robenidine, and salinomycin did not have a meaningful effect on the variables measured when fed to White Leghorn layers.

Ten-mo-old broiler feeds were fed nicarbazin (NCZ) at 0, 25, 50 and 100 ppm of their diet for 2, 4, or 6 days to simulate accidental contamination of their feed with the medicant. Reduced egg production was observed in all treatments except 25 and 50 ppm NCZ for 2 days. A consistent reduction in egg weight occurred only at the maximum treatment level of 100 ppm for 6 days. Reduction in hatchability was generally evident by Days 5 and 6 of the experiment except for the lowest treatment of 25 ppm NCZ for 2 days. Due partially to the low number of eggs set, no statistically significant reduction in hatchability was seen for the group receiving 50 ppm NCZ for 4 days, but hatchability had dropped over 17 percentage points (from 93.3 to 75.5%) by Days 5 and 6 of the experiment, and continued to drop to a low of 31% on Days 11 and 12 of the experiment. Shell pigmentation was the most sensitive characteristic measured, with significant depigmentation occurring after only 2 days of feeding 25 ppm NCZ. Generally, the severity and duration of effects were in proportion to medicant concentration and length of treatment time. Fertility was not influenced by the medicant.

The ultrastructure of guinea spermatozoa was characterized by transmission and scanning electron microscopy. The average lengths and widths (measured at the widest points) of the segments were as follows: acrosome, 1.8 x .47 mu; nucleus, 12.8 x .49 mu; midpiece, 3.9 x .59 mu; flagellum, 59 x .52 mu. Thus, the guinea sperm cell is slightly smaller than the chicken or turkey spermatozoon. The ultrastructure of the guinea spermatozoon was similar to that of the chicken and turkey with two exceptions: 1) the mitochondria had cristae aligned parallel and oblique with respect to the outer limiting membrane and 2) there was no proximal centriole, the distal centriole projected into the implantation fossa with "arms" of the nonstriating connecting piece extending laterally from the centriole to the implantation fossa.

Four brown egg strains were used to study the effect of rearing diets on growth and performance. The treatments were arranged in a 4 x 3 factorial with two replicates of 45 birds. The control diet was formulated and fed to National Research Council recommendations. Birds on reverse protein (RP) were fed diets with 13, 16, and 19% protein and those on low protein (LP) regimen received a 13.5% protein diet with amino acids adjusted on a megacalorie basis to approximate the control diet. At 20 weeks of age pullets were caged and fed a standard layer diet. Logistic curves were fitted to the growth data by a nonlinear least squares method and the parameters of each curve analyzed. No significant strain x diet interactions were observed. There were significant differences among strains in weight gain and feed intake. Dietary regimens had no significant effect on total gain and feed intake. However, diets significantly altered age at one-half maximum growth or inflection point (alpha) and mean growth rate (rho). Inflection point of the growth curve was significantly delayed in birds fed RP and LP diets. Although apparent conversion was not affected by diets, the partition coefficients at any time (t) for maintenance (beta mt) and gain (beta gt) were altered. Neither strain nor dietary regimens affected abdominal fat or organ weights at the end of the rearing period. No significant effect of rearing dietary regimens was detected in age at 50% production or peak production, feed conversion, feed intake, livability, liver fat, abdominal fat, or shell strength. The reverse-protein regimen significantly depressed egg weight. The results of the study indicate that 1) the rearing dietary regimens were adequate for strains of different body weight and egg output characteristics; 2) dietary alteration of growth curve parameters failed to influence production, feed intake, mortality, shell strength, livability, liver fat, or abdominal fat during the production period.