Search

Addition of the hypocholesteremic agent Probucol ((4,4'-isopropylidine dithio)-bis(2,6-di-t-butyl-phenol)) to the diet of laying hens at up to 1% significantly reduced egg yolk cholesterol content (mg/g yolk) without impairment of rate of egg production, egg weight, shell strength, albumen quality, or other production related parameters. Dietary concentration of .1% Probucol significantly reduced yolk cholesterol within 2 weeks after feeding. Higher concentrations did not further reduce yolk cholesterol. Probucol at .025% reduced egg yolk cholesterol within 4 weeks after feeding, but after 8 weeks of feeding, eggs from hens fed .025% Probucol did not differ significantly in yolk cholesterol from those fed the basal unsupplemented diet. This suggests possible adaptation in cholesterol synthesis by the laying hen.

Two experiments were conducted to evaluate the response of broiler chickens to addition of bacitracin methylene disalicylate (BMD) to diets containing salinomycin. In each experiment, five tests were conducted at different locations. In Experiment 1, all diets contained 66 mg salinomycin/kg of diet for the first 42 days and either 0 or 33 mg BMD/kg of diet for the entire 49-day feeding period. In Experiment 2, all diets contained 66 mg salinomycin and 50 mg roxarsone/kg of diet for the first 42 days and either 0, 11, 33, or 55 mg BMD/kg of diet for the entire 49-day feeding period. In Experiment 1, addition of 33 mg BMD/kg of diet significantly (P less than .05) improved body weights and feed utilization. Results were similar in all five tests. In Experiment 2, addition of 11, 33, or 55 mg BMD/kg of diet significantly (P less than .05) increased body weights. In one location the addition of 55 mg BMD/kg of diet resulted in no significant difference in body weight compared with those fed the unsupplemented diet, but in all other locations the response was similar. Addition of 33 or 55 mg BMD/kg of diet resulted in improved (P less than .05) feed utilization when all tests were combined. Feed utilization was not improved in all locations by the addition of BMD.

Studies were conducted at six locations over a 7-yr period to evaluate the response of broiler chickens to bacitracin methylene disalicylate (BMD) and roxarsone in the presence of diets containing 3 ppm halofuginone/kg feed. Treatments consisted of a 2 x 2 factorial arrangement with 0 or 55 mg BMD and 0 or 50 mg roxarsone/kg feed. These additives were fed beginning with day-old chicks and were removed 6 days before termination of the study, which varied in length from 48 to 56 days among locations. Body weights were significantly improved (P less than .05) by the addition of either BMD or roxarsone with a significant interaction (P less than .05) between BMD and roxarsone. Roxarsone improved body weights only in the presence of BMD. Feed utilization was significantly (P less than .05) improved by addition of either BMD or roxarsone, with no interaction between the two products.

A group of 2-week-old turkey poults was inoculated with a pathogenic strain of Alcaligenes faecalis. One week later, half the group was injected with a long-acting oxytetracycline formulation. Poults were examined post-mortem on days 3, 5, and 10 post-treatment. Swabs were taken of the trachea, sinus, and lung of each poult. Poults were observed closely for clinical signs, and appropriate tissues were taken for histopathology. Results showed no evidence of therapeutic effect on A. faecalis infection in vivo, even though the organism was highly sensitive in vitro. Six-week-old turkeys were inoculated intramuscularly with 3.7 X 10(3) organisms of the P-1059 strain of Pasteurella multocida. Immediately following inoculation, half the group was treated with the long-acting oxytetracycline. Ninety percent of the untreated poults were dead 72 hours postinoculation, whereas none of the treated turkeys died. No evidence of any clinical disease was observed in the treated group during the 8-day observation period. The long-acting oxytetracycline product was highly efficacious in preventing disease caused by experimental inoculation with the P-1059 strain of P. multocida.

Six trials were conducted at different locations to examine the response of broiler chickens to roxarsone and bacitracin in the form of bacitracin methylene disalicylate (BMD) in the presence of the anticoccidal narasin. All diets contained narasin (80 mg/kg) and were fortified with a factorial arrangement of roxarsone (0 to 50 mg/kg) and BMD (0 or 55 mg/kg). Broilers were grown to market weights with narasin and roxarsone removed from the diets for the final 5 days. Addition of both roxarsone and BMD resulted in significant (P less than .05) improvements in body weight and feed utilization. Response to roxarsone for feed utilization was influenced to some extent by the presence or absence of BMD. Although the response to roxarsone was always positive, the degree of response was lessened by the presence of BMD. This resulted in a significant (P less than .10) interaction between roxarsone and BMD for feed utilization but not for body weight.

Four experiments were conducted to examine the response of broiler chickens to different levels of niacin. Practical-type diets, calculated to contain from 20.7 to 23.7 mg niacin per kg from intact ingredients, were fortified with a complete vitamin mixture which provided 33 mg supplemental niacin per kg of diet, in excess of the National Research Council (1977) suggested requirement of 27 mg per kg through 6 weeks of age. A niacinamide supplement was used to provide additional levels of 0, 33, or 66 mg per kg. Diets differed in content of added fat and energy levels in two of the experiments and in the presence or absence of animal protein sources in two others. The addition of niacinamide at 33 and 66 mg per kg to a diet already supplemented with 33 mg per kg from a complete vitamin premix, calculated to exceed the present NRC suggested requirement, resulted in improved body weight gains with sex differences noted in some experiments. Feed utilization was improved in some studies. There was no effect on the amount of abdominal fat or carcass dressing percentage. The results of these studies indicate that the modern rapidly growing broiler chick may require niacin levels greater than those generally recommended by the National Research Council (1977), which are based largely on studies where performance was considerably lower than obtained with the modern strains of broilers.

Three experiments were conducted by sampling a total of 15,705 eggs from Leghorn hens fed diets varying in methionine, Na, and Ca content. In Experiment 1, birds of four different ages were housed in a common environment and fed diets containing between .233 and .383% methionine. In Experiment 2, birds of five different ages were housed in a common environment and fed diets containing .15, .30, and .45% Na and .25, .45, and .65% nonphytate phosphorus (NPP). In Experiment 3, eggs were sampled from 42 to 62 wk of age in 4-wk intervals from hens fed diets containing from 3 to 9% Ca in increments of 1.5%. Feeding lower levels of methionine (.233%) produced significantly lower egg weights and greater shell strength but at the expense of a decline in egg production at early ages. Reducing the NPP level from .65 to .25% produced lower egg weights and greater shell strength. A corresponding drop in production was not observed except at the .45%-Na level. No significant effects of Na on shell strength were observed. Higher Ca levels produced greater shell strength and had variable effects on egg weight. Increasing the Ca level beyond 6% resulted in a significant decline in production. Regression analyses indicated that within a population, the relationship between egg weight and shell strength is positive. In some instances, the relationship was curvilinear, where the positive association between egg weight and shell strength decreased with increasing egg weights.

Five trials were conducted at various locations to determine the response of broiler chickens to the addition of zinc bacitracin to diets containing both salinomycin and roxarsone. Results indicate that when a combination of salinomycin and roxarsone is used as an anticoccidial, the addition of zinc bacitracin at 33 or 55 mg/kg diet will improve growth rate and feed utilization by broiler chickens. Regression of body weight and feed utilization on dietary levels of zinc bacitracin indicated that each milligram of zinc bacitracin in the diet increased the 49-day weight of broiler chickens by .92 g and reduced the feed required per gram of gain by .0012 g.

Forty 6-week-old large white commercial turkeys were injected subcutaneously with a long-acting oxytetracycline formulation (69 mg/lb). The turkeys were divided into four groups of 10 birds each, and the birds in each group were bled twice at different times between 4 and 144 hours postinjection (PI) to determine serum levels of oxytetracycline. Two additional groups of turkeys were also given the long-acting oxytetracycline formulation mixed with either neomycin or a bacterin for Pasteurella multocida to determine if either of these compounds interfered with absorption of the oxytetracycline. Serum levels of oxytetracycline were 5.38 micrograms/ml, 1.59 microgram/ml, and 0.93 microgram/ml at 24, 48, and 72 hours PI, respectively, following an average dose of 69 mg/lb of body weight. These levels are all considered therapeutic. There appeared to be no interference with absorption of oxytetracycline when mixed with either neomycin or the bacterin. Tissue residues of oxytetracycline in the muscle, liver, and kidney were within tolerance levels by 3 weeks PI.