The effect of added complex carbohydrates or added dietary fiber on necrotic enteritis lesions in broiler chickens.

Two trials utilizing two corn diets and four wheat diets were conducted. In Trial 2, all chicks were crop-infused at 9 d of age with Eimeria acervulina. In both trials, a broth culture of Clostridium perfringens was mixed with the diets for 3 consecutive d. Necrotic enteritis lesion scores were lowest in chickens consuming the corn diet with no C. perfringens and highest in chickens fed the wheat diets with C. perfringens. Chickens consuming a wheat diet with no added complex carbohydrates or added fiber exhibited the highest lesion score. Chickens on wheat diets with 4% new, ground, pine shavings had intestinal lesion scores intermediate to those of chickens that consumed the wheat or corn diets. Chickens consuming corn diets yielded the lowest lesion scores. Chickens provided diets containing either guar gum or pectin were not fully consumed and thus probably reduced the number of challenge organisms ingested.

The effect of brooding temperature on broiler performance.

In response to the energy crisis of the 1970s, this laboratory recommended that initial brooding temperatures for broilers be reduced to 29.4 C from 32.2 or 35 C. Because environmental temperature has been implicated in the ascites syndrome, this work was conducted to see whether the recommended brooding temperature of 29.4 C the 1st wk, 26.7 C the 2nd wk, and 23.9 C the 3rd wk would be satisfactory for broiler production when compared with higher brooding temperature regimens starting at 32.2 or 35 C. Brooding chicks at a temperature of 29.4 C the 1st wk, 26.7 C the 2nd wk, and 23.9 C the 3rd wk did not adversely affect broiler performance at 6 wk of age, when compared with higher brooding temperature regimens. Under the conditions of this experiment, brooding chicks at a temperature of 29.4 C the 1st wk, 26.7 C the 2nd wk, and 23.9 C the 3rd wk was satisfactory when compared with the higher temperature brooding regimens. Mortality due to ascites and total mortality significantly increased for broilers brooded in the negative control temperature regimen of 26.7 C the 1st wk, 23.9 C the 2nd wk, and 21.1 C when compared with some or all of the higher brooding temperature regimens. Heat loss calculations based on a commercial setting show an 18% savings in liquified petroleum (LP) gas usage for chicks brooded at 29.4 vs 35 C and a savings of 10% in LP gas usage for chicks brooded at 29.4 vs 32.2 C on a winter day.

The effect of early feed restriction on broiler performance.

In an attempt to determine the effect of early feed restriction on broiler performance, nine trials were conducted. Feed restriction was based on previous 24-h feed consumption values of the full-fed control groups. Feed restriction was from either 7 to 14 d of age (Trials 1 to 5) or 8 to 16 d of age (Trials 6 to 9). The treatments for Trials 1 to 5 were 90, 75, and 60% of previous 24-h feed consumption of full-fed controls. The treatments for Trials 6 to 9 were 80 and 60% of previous 24-h feed consumption of full-fed controls. Early feed restriction did not affect abdominal fat. Early feed restriction did improve feed conversion (grams of feed:BW). Males and females equated at 41 d of age for an 8% reduction (90% feed restriction) at 14 d of age when compared with full-fed control broilers. Neither females or males could overcome a 17 or 18% weight reduction (75% feed restriction) at 14 d of age by 41 d of age. At 48 or 49 d of age, both males and females could equate in weight with full-fed control broilers for a weight reduction of 27 and 31% (60% feed restriction) at 16 d of age. Mortality or deformed legs did not differ between any of the comparisons.

The effect of meal feeding on small intestine weight.

Two trials were conducted using feed forms of pellets and mash to determine whether parts of the digestive tract (small intestine) were enlarged by meal feeding. Results obtained show that meal feeding of broilers significantly increases small intestine weight for both mash and pellet broiler groups when compared with continuously fed broilers. The body weight, feed conversion, and mortality did not differ between the continuous-fed versus meal-fed groups. Pelleting the diet during the growing period (3 to 6 wk of age) significantly improved both growth rate and feed conversion of broilers.

The effect of temperature, dietary energy level, and corn particle size on broiler performance.

Experiments were conducted to study the effect on broiler performance of grinding corn with different hammer mill screen openings (HMSO). Corn for Trials 1 and 2 was ground through HMSO of 3.18 or 9.59 mm and broilers were grown at 15.5 and 26.6 C in Trial 1 and at 26.6 C in Trial 2. Dietary energy levels used from 22 to 42 days were 3,050 and 3,230 kcal ME/kg for Trial 1 and 3,230 and 3,330 kcal ME/kg in Trial 2. In all starter and finisher diets, lysine and sulphur amino acid concentrations were similar on a megacalorie basis. In Trials 3 and 4, HMSO were 3.18, 4.76, 6.35, and 7.94 mm. Corn ground through a HMSO of 9.59 mm significantly reduced body weight and feed:gain ratio in Trials 1 and 2 at 21 days as compared with corn ground through an HMSO of 3.18 mm. At 42 days, body weights were reduced when corn was ground through 9.59- and 3.18-mm HMSO for the starter and finisher diets, respectively, as compared with those fed with the corn ground through a 3.18-mm HMSO in the starter diet. In Trials 3 and 4, significant differences in body weight and feed:gain ratios at 21 days were not noted for feed containing corn ground through an HMSO of 3.18, 4.76, 6.35, or 7.94 mm.

The effect of light and environmental temperature on broiler digestive tract contents after feed withdrawal.

Contamination from the digestive tract is a persistent problem in broiler processing. Two experiments were conducted to determine the effects of lighting and environmental temperature on quantity of crop, gizzard, and small intestine contents during feed withdrawal. Broilers were on litter with a feeding regimen of 1.5 h on feed and 4.5 h off feed for 1 or 2 days. The withdrawal period began at the end of a 1.5-h feeding period. In the first experiment, broilers were cooped or left on the floor with and without lights. Crop contents of lighted broilers at 21 C were reduced 2 h after feed withdrawal for broilers on litter and in coops. In another experiment, broilers on litter were maintained at 18 and 27 C in light or in darkness. Lighting reduced crop contents 4 h after feed withdrawal but increased the contents of the small intestine 2 h after feed withdrawal at both temperatures. These results indicate that crop clearance is improved by lighting both before and after cooping.

Decreased egg production in commercial laying hens fed zearalenone- and deoxynivalenol-contaminated grain sorghum.

In an experiment to determine the effect of corn vs. grain sorghum on performance of laying hens, egg production decreased significantly in the grain sorghum-fed hens in each of two trials starting 24 weeks after the trials began. Necropsy of chickens fed both diets revealed buccal ulceration at the ventral aspect of the oral cavity and squamous metaplasia of the esophageal glands and submaxillary salivary glands. Lesions were much more severe in the sorghum-fed birds than in the corn-fed birds. Analysis of the grain sorghum and corn revealed the presence of mycotoxins. Zearalenone and deoxynivalenol were present in the grain sorghum, and a lower amount of deoxynivalenol and a trace of aflatoxin B1 were found in the corn. Although mycotoxin levels were low, interaction between these mycotoxins and others may have decreased egg production.

Digestive tract clearance of broilers cooped or deprived of water.

Feed is withdrawn from broilers to facilitate digestive tract clearance before processing. This research examined the effects of cooping and water deprivation on contents of the digestive tract during feed withdrawal in two experiments. Broilers were reared to 48 days of age on litter in a windowless house. Corn-soybean meal diets and water were provided ad libitum. In the first experiment, broilers were continuously fed before feed withdrawal. In the second experiment, broilers were placed on a meal-feeding regimen of 1.5 h on feed and 4.5 h off feed for 42 h prior to feed withdrawal. Withdrawal began at the end of a 1.5-h feeding period. At the time of feed withdrawal, broilers were cooped, left on litter without water, or left on litter with water available. At 2, 4, 6, and 8 h after withdrawal, ten broilers from each treatment were killed and the crop, proventriculus plus gizzard, and small intestine were removed. The weight of the contents of each segment was determined. Water deprivation did not change the weight of contents in any segment. Cooped broilers retained digesta in the crop and proventriculus plus gizzard for a longer time than broilers on litter. The combination of meal feeding and cooping soon after feed withdrawal greatly increased the quantity of digesta in the crop 8 h after feed withdrawal. Cooping should be delayed until the crop is empty. Meal feeding increases the time required to accomplish this.

F strain Mycoplasma gallisepticum vaccination of post-production-peak commercial Leghorns and its effect on egg and eggshell quality.

Forty-five-week-old commercial leghorns negative for antibodies to Mycoplasma gallisepticum (MG) and M. synoviae were vaccinated with high-passage F strain MG (FMG). Hens were confined in modified Horsfall-Bauer isolation units through 60 weeks of age. Egg production (% hen day) and parameters of egg and eggshell quality were monitored, including egg weight, eggshell strength, Haugh unit score, pimpling, and blood/meat spot incidence. Egg production was significantly lower (P less than 0.05) for FMG vaccinates than controls (down 5.76% and 5.80% in Trials 1 and 2, respectively). However, vaccinates and controls did not differ significantly in eggshell strength, shell thickness, pimpling, or blood/meat spot incidence. Haugh unit scores were significantly (P less than 0.05) greater for FMG vaccinates. At necropsy, all reproductive tracts appeared grossly normal. These studies suggest that high-passage FMG vaccination of post-production-peak hens does not adversely affect oviduct function.

Position of Meckel's diverticulum in broiler-type chickens.

In each of three trials broiler-type chickens were used to determine whether Meckel's diverticulum resides in a constant position along the intestinal tract. Chickens were provided a basal diet ad libitum through 49 (Trials 2 and 3) or 52 days of age (Trial 1). Body weight and total intestine length as well as the lengths of the intestine from the gizzard to Meckel's diverticulum (GMD) and from Meckel's diverticulum (MD) to the cecal openings (MDC) were then recorded. When intestine length was expressed as a percentage of body weight, significant differences were noted between sexes. However, no significant differences were observed between sexes for either GMD or MDC relative to total intestinal length. Results of this study indicate that MD resides in a constant position along the length of the intestinal tract. This constancy of position supports the use of MD as a boundary point of the intestine.

Weight gain of summer-reared egg-type pullets fed pellets versus mash.

In an attempt to increase weight gain of egg-type pullets reared under high summer temperatures, pullets were fed feed in either pellet or mash form. Under high temperature rearing conditions, pelleting the diet did not significantly increase 12 to 20-wk body weight gain when compared to effects of the diet fed in mash form. Under a moderate temperature regimen (21 C), pelleting the diet did significantly increase 12 to 20-wk body weight gain in contrast to the effects of the diet fed in mash form.

Cyclic watering of broiler cockerels.

Two trials were designed to compare the performance of broilers receiving free access to water with those receiving cyclic access to water. Birds that received water in cyclic pattern were presented water by the activation of waterers for 15 min in each 3-h cycle (Trial 1) or 30 min in each 4-h cycle (Trial 2). In each trial, the control group received water ad libitum. Feed and water consumption and body weight were reduced in the cyclic-watered birds after 21 days of age in Trial 1 and were not different in the cyclic-watered birds in Trial 2 when compared with values for controls. Water:feed ratio and feed conversion values of the cyclic-watered birds were not altered by the cyclic watering regimens used in Trials 1 and 2. Observations of drinking patterns in Trial 2 demonstrate that the cyclic presentation of water can induce meal-drinking in cyclic-watered birds, but the feeding pattern of these birds was not altered. These data demonstrate that alteration of drinking activity can be accomplished without affecting growth and feed efficiency, and that altered drinking activity does not necessarily alter feeding activity.

Effect of environmental temperature and feeding regimen on quantity of digestive tract contents of broilers.

Carcass contamination from contents of the digestive tract during processing is a recurring problem for the broiler industry. Environment and feeding regimen are often implicated as causative factors. The effects of environmental temperature and meal feeding on passage of feed through the digestive tract of broilers were examined. Broilers were reared in environmental chambers in five experiments. In the first experiment, environmental temperatures were constant temperatures of 16 and 27 C and cycles of 16-24-16 and 24-35-24 C and rate of passage of feed through the digestive tract (ROP) was determined with ferric oxide. Temperature did not consistently affect ROP. In the other four experiments, various environmental temperatures were investigated and broilers were fed continuously or for 12 or 16 h/day. Contents of the crop, proventriculus plus gizzard, and small intestine were weighed 2, 4, 6, and 8 h after feeding withdrawal. Environmental temperature did not directly affect the movement of digesta but the feeding regimen affected the quantity of digesta in some segments of the tract. Environmental temperature may have indirectly affected the quantity of feed in the crop by affecting the quantity of feed consumed. Limiting the feeding period resulted in retention of digesta in the crop of some broilers for an extended period. This increased the variability in quantity of crop contents. A feeding regimen X temperature interaction resulted in increased small intestine weight for meal-fed broilers at 16 C.

Effect of beak trimming on body weight and feed intake of egg-type pullets fed pellets or mash.

Pelleted and mash feed were provided in each of two trials. In the first trial, it was noted that the pullets did not eat the feed that was offered in pellet form. Type of beak trimming appeared to be involved in lowering feed intake. The second trial demonstrated that pullets with either the top beak or both beaks trimmed (block cut) approximately 2 mm from the nostril when offered pellets or mash did not eat feed in pellet form as readily as that in mash form.

Body temperature of acclimated broilers during exposure to high temperature.

Short-term acclimation to high temperatures increased resistance of broilers to heat exposure. Two trials were conducted to determined the effect of acclimation on body temperature (Tb) during heat exposure. Broilers, 46-days old, were maintained at control or acclimating temperatures for 4 days. The control temperature was a constant 21 C with a 10 C dewpoint, and the acclimating temperature was a diurnal cycle of 24-35-24 C with a constant 21 C dewpoint. During the 4th day, broilers of both groups were exposed to temperatures of 41 C and 23 C dewpoint for 210 min. Body temperature was determined at the beginning of the heat exposure and at 30-min intervals until the end of the exposure. The Tb of both groups increased throughout heat exposure, but acclimated broilers had significantly lower Tb than control broilers from 90 through 210 min. Acclimated broilers had significantly lower heat stress mortality. The data show that acclimated broiler's Tb rises upon exposure to heat but that acclimation gives the capacity to stabilize Tb above normal Tb. The data also suggest Tb is preferable to mortality as a measure of acclimation in broilers.

Use of ammonium chloride and sodium bicarbonate in acute heat exposure of broilers.

Ammonium chloride (NH4Cl) and sodium bicarbonate (NaHCO3) were added separately to the drinking water of 42- to 52-day-old broilers. Birds were given access to the water ad libitum for a total of 42.5 hr consisting of 18.5 hr prior to an 8-hr interval of severe heat exposure and a further 16 hr-post exposure. Water and feed intake during the treatment period were unaffected by either NH4Cl at 6.25 g/liter (.63%) of distilled water (DW) or NaHCO3 at 3.15 g/liter (.32%) DW. Water intake was increased by approximately 20% in birds given water containing 6.25 g of NaHCO3/liter (.63%) DW, while both feed and water intake were severely limited by NH4Cl at 31 g/liter (3.1%) DW. Blood pH of birds was substantially lowered by consumption of NH4Cl, while consumption of NaHCO3 did not significantly affect blood pH. Blood pH of all treatments increased during the heat exposure period and declined afterward; however, blood pH change appeared to be more pronounced for birds receiving the NH4CL. A correlation coefficient (r = -.31) existed between blood pH and mortality, while a correlation (r = -.72) was demonstrated between water consumption and mortality.

Atmospheric ammonia and incidence of blood spots in eggs.

A study was conducted to determine if atmospheric ammonia causes an increase in blood spots in eggs. Results show that atmospheric ammonia did not cause an increase in the number of blood spots in eggs.

Effect of acclimation and heat stress on thyroid hormone concentration.

In three trials, broilers were exposed to either moderate-constant or high-cyclic temperatures for 3 days. Broilers in both treatments were exposed to 41 C and high humidity over a 4- to 6-hr period on the 4th day. Blood samples, collected before and at the end of the heat exposure, were assayed for thyroid hormones. Neither acclimation nor severe heat exposure consistently affected triiodothyronine (T3) or thyroxine (T4) concentration. It appears the mechanism of short-term acclimation involves endocrine or physiological responses other than changes in circulating thyroid hormone concentrations.

Age and dietary energy effect on broiler abdominal fat deposition.

Three trials were conducted to determine when abdominal fat is deposited in relation to age and dietary energy level for broilers. Results show that the amount of abdominal fat as a percentage of body weight increased as age (36 to 54 days) and dietary energy level (3100 to 3325 metabolizable energy kcal/kg) increased. During the 36 to 54-day period, the weight of the broilers increased 75% for males and 72% for females. During the 36 to 54-day period, abdominal fat expressed as a percentage of body weight increased 23% for males and 38% for females.

Egg production, egg weight, eggshell strength, and mortality in three strains of commercial layers vaccinated with F strain Mycoplasma gallisepticum.

Three strains of commercial leghorns vaccinated at 17 to 22 weeks of age with F strain Mycoplasma gallisepticum (MG) were maintained through 117 weeks of age. The three strains differed in both mortality and percent egg production per hen housed; however, the strains did not differ in egg weight (EW), eggshell strength (ESS), or percent daily egg production. Results of this study indicate EW and ESS for F strain MG-vaccinated hens follow patterns previously reported for uninfected layers. Further, mortality may account, in part, for differences in percent egg production per hen housed between strains of F strain MG-vaccinated hens.