Performance of commercial laying hens when six percent corn oil is added to the diet at various ages and with different levels of tryptophan and protein.

Three experiments were conducted to evaluate the use of corn oil in the diet of commercial layers as a method of increasing egg weight. In the first experiment, the performance of commercial layers receiving 6% added corn oil beginning at 18 to 30 wk at 2-wk intervals was evaluated. In the second experiment, comparisons were made between performance of young and old commercial layers when 6% corn oil was added to the diet. The third experiment was conducted to evaluate the effects upon commercial layers when 6% corn oil was added to diets varying in Trp content. In experiment 1, egg weights increased during the first 2 wk that corn oil was added to the diet. During this time, the intake of Trp was greater than or equal to the hen requirements. However, during the last 2 wk of the experiment, when Trp intakes were low, egg weights decreased when corn oil was added to the diet. In experiment 2, egg weights from young and old hens increased during the first 2 wk after corn oil was added to the diet. During the last 2 wk, egg weights from young hens decreased, whereas egg weights from old hens increased. In experiment 3, egg weight was not affected when the diet contained 0.166 or 0.176% Trp. However, egg weights significantly increased when corn oil was added to the diet containing 0.193% Trp. The data in these experiments indicate that the diet of a laying hen must contain a high level of Trp to get an increase in egg weight from the addition of corn oil to the diet. Also the need for other amino acids must be met. Therefore, the hen eats to meet her energy requirement for maximum egg production, and her amino acid intake determines the egg weight.

Threonine requirement of commercial laying hens fed a corn-soybean meal diet.

Two experiments were conducted with Hy-Line W36 hens to evaluate their Thr requirement in a corn-soybean meal diet. Eight experimental diets were used in Experiment 1 with graded levels of Thr: 0.53,0.50, 0.48, 0.45, 0.42, 0.40, 0.37, and 0.35%. Seven experimental diets were used in Experiment 2 with graded levels of Thr: 0.58, 0.53, 0.50, 0.48, 0.45, 0.42, and 0.40%. Supplemental amino acids (AA) were added to all diets to ensure that Thr was the first-limiting AA. Egg production (EP), egg mass (EM), and daily Thr intake were significantly increased with increasing dietary Thr levels. Broken-line regression indicated a daily Thr requirement of 439.0 and 462.1 mg per hen per d in Experiment 1 and of 393.9 and 447.1 mg per hen per d in Experiment 2 for EP and EM, respectively. The Thr requirements to produce 1 g of EM were 8.76 and 9.44 mg in Experiments 1 and 2, respectively.

Betaine does not improve performance of laying hens when the diet contains adequate choline.

An experiment was conducted with Hy-Line W36 hens to determine possible benefits from adding betaine to the diet of commercial laying hens. There was no benefit from the substitution of betaine for choline as measured by egg production, egg weight, egg content, or weight gain.

Re-evaluation of the isoleucine requirement of the commercial layer.

An experiment was conducted with Hy-Line W36 hens to re-evaluate their Ile requirements from a corn-soybean meal diet. Eight experimental diets were fed with Ile levels of 0.60, 0.57, 0.54, 0.51, 0.48, 0.45, 0.42, and 0.39%. Supplemental amino acids (AA) were added to ensure that ILe was the first-limiting AA. Increasing levels of Ile above 0.51% significantly increased egg production (EP), egg weight (EW), and egg mass (EM). Egg production, EW, and EM decreased each time the Ile content of the diet was decreased. Feed consumption (FC) and energy intake were not significantly decreased until the diet contained 0.45% Ile, and, at this time, BW was significantly reduced. Broken-line regression indicated a daily Ile requirement of 449.8, 497.0, and 469.0 mg/d for EP, EW, and EM, respectively, which indicated a requirement of 9.30 mg Ile/g EM.

Evaluation of valine requirement of the commercial layer using a corn-soybean meal basal diet.

An experiment was conducted with Hy-Line W-36 hens to evaluate the Val requirement in a corn-soybean meal diet. Eight experimental diets were fed with Val levels of 0.700, 0.665, 0.630, 0.595, 0.560, and 0.525%. A positive control (0.765% Val) was fed. Egg production (EP) was increased by addition of Val to 0.630%. Egg weight (EW) was increased by addition of Val to 0.655%. Broken-line regression indicated a daily Val requirement of 592.5, 677.7, and 619.0 mg/hen per d for EP, EW, and egg contents (EC), respectively. This requirement was 13.1 mg/g of EC.

Evaluation of the isoleucine requirement of the commercial layer in a corn-soybean meal diet.

An experiment was conducted with Hy-Line W36 hens to evaluate their Ile requirement in a corn-soybean meal diet. Five experimental diets were fed with Ile levels of 0.61, 0.58, 0.55, 0.52, and 0.49%. Supplemental amino acids (AA) were added to ensure that Ile was the first-limiting AA. Two diets with 0.55 and 0.52% Ile were also fed with higher levels of supplemental AA. A positive control (0.67% Ile) with only Met supplementation was fed, which had previously been shown to support maximum performance. All levels of Ile addition significantly increased egg production (EP), egg weight (EW), and egg contents (EC). Broken-line regression indicated a daily Ile requirement of 589.2, 601.2, and 601.4 mg per day for EP, EW, and EC, respectively, which indicated a requirement of 12.6 mg Ile per gram of EC.

Evaluation of tryptophan requirement of the commercial layer by using a corn-soybean meal basal diet.

An experiment was conduced with Hy-Line W36 hens to evaluate the requirement for Trp in a corn-soybean meal diet. Seven experimental diets were fed with Trp levels of 0.12, 0.13, 0.14, 0.15, 0.16, 0.17 and 0.18%. Supplemental amino acids (AA) were added to all diets to ensure that Trp was the first-limiting AA. A positive control diet (0.20% Trp) with Met supplementation was fed that had previously been shown to support maximum performance. Egg production (EP), egg weight (EW), and egg content (EC) were significantly increased by the addition of Trp to the basal diet. Broken-line regression indicated the Trp requirement for EP and EC was 139.8 and 149.0 mg per hen/d, respectively, for EP and EC when hens had a daily EC of 45.4 g per hen/d.

Tryptophan requirement of the commercial hen.

An experiment was conducted to determine the Trp requirement of the commercial laying hen. A corn-soybean meal diet was used that contained gelatin, which is low in Trp. Tryptophan was the first-limiting amino acid in this diet. Methionine, Lys, Arg, Thr, Val, and Ile were added to ensure that they were not deficient. Experimental diets containing 0.0, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.12% Trp were fed, and a corn-soybean meal diet served as the positive control. Egg production (EP), egg mass (EM), and egg content (EC) were significantly increased by the addition of supplemental Trp. Broken-line regression indicated that the Trp requirement for EP and EC for this experiment was 136.0 (R2 = 0.81) and 136.5 (R2 = 0.82) mg per hen per d, respectively. These hens produced 43.5 g of EC, resulting in a Trp requirement of 3.14 mg/g of EC. Therefore, assuming an output of 50 g of EC, we suggest 157 mg per hen per d as the requirement for maximum production of EC.

Ability of commercial laying hens producing different egg outputs to meet their methionine and energy requirements when fed the same diet.

An experiment was conducted to determine whether commercial laying hens with different egg outputs could meet their Met requirement when fed the same diet. Three groups of hens were selected with either low, medium, and high egg output. Body weight of hens was positively related to egg output. As egg output increased, feed consumption increased. This resulted in essentially the same amount of energy consumed per gram of egg content (EC) for all three groups. Egg weight was greatest with hens producing the greatest EC. The Met intake of hens was increased with increased EC; however, the Met per gram of EC was not different for the three groups of hens. These data indicate that the Met and energy requirements of commercial layers can be met with one feed when individual hens produce different amounts of EC.

Correlation of plasma calcium with experimentally elevated cholesterol and triglycerides in laying hens.

An experiment was conducted to determine the relationship between plasma Ca, cholesterol, and triglycerides in commercial laying hens. A 2 x 2 factorial arrangement of treatments was used with two levels of dietary iodine (0 and 5,000 ppm) from KI and two levels of beta-estradiol (0 and 12 mg in a single subcutaneous injection), in a corn oil carrier. Feeding iodine or injecting beta-estradiol resulted in increased plasma Ca, cholesterol and triglycerides. The increases were additive for the two treatments. Plasma Ca and cholesterol was significantly correlated. Plasma Ca was negatively correlated with triglycerides when the hens were injected with beta-estradiol. Cholesterol and triglycerides were correlated when hens were injected with beta-estradiol. However, feeding KI decreased the correlation between Ca and triglycerides, and cholesterol and triglycerides.

Sodium requirement for broiler breeder hens.

Two experiments were conducted with Arbor Acres hens to determine their Na requirement. Sodium chloride was added to a corn-soybean meal diet to furnish daily intakes of 35, 65, 95, 125, and 150 mg per hen in Experiment 1. The 150 mg level was replaced with 180 mg in Experiment 2. The hens were maintained in floor pens with wood shavings used as litter. Experiment 1 was conducted for 9 wk and Experiment 2 for 12 wk. Egg production was significantly reduced during Week 4, when the hens had an intake of 35 mg Na/d. Egg production was reduced by Week 7 when the diet furnished 65 mg/d. Plasma Na was reduced and plasma K increased when the intake was 35 or 65 mg/d. Performance data from 6 to 9, and 6 to 12 wk were used in Experiments 1 and 2, respectively, to determine the daily Na requirement. The daily requirement for maximum production was 113.8 and 96 mg and the requirement for egg mass was 105 and 100 mg in Experiments 1 and 2, respectively.

Re-evaluation of the methionine and protein requirements of the broiler breeder hen.

Three experiments were conducted to study the Met and protein requirements of Arbor Acres broiler breeder hens. Broken line regression analysis in Experiments 1 and 3 indicated the Met requirement was 335 and 323 mg/d, respectively, with a production of a daily egg content (EC) of 42.3 or 43.0 g. A broken line could not be fitted to the data in Experiment 2. Therefore, this procedure could not be used to calculate a requirement. An average of 7.83 mg Met was required to produce 1 g of EC. Using this value, the requirement for the three experiments would be 344 mg at the level of EC produced in these experiments. The requirement would be higher with either a higher rate of lay or with larger eggs.

A re-evaluation of the protein and lysine requirement for broiler breeder hens.

An experiment was conducted with 32-wk-old Arbor Acres broiler breeder hens to determine their requirement for Lys and protein. Diets were fed with Lys levels ranging from .545 to .380% and with protein levels ranging from 11.46 to 8.90%, respectively. A daily intake of 845 mg of Lys per hen per d was required for maximum egg production, egg mass, and egg content. A daily intake of 18.07 g protein was required with a corn-soybean meal diet containing no supplemental amino acids. However, when Met and Lys were added to the diet, daily protein intakes of 15.53 and 16.37 g supported performance that was not significantly different from performance of hens receiving higher levels of protein.

The relationship of egg cholesterol to serum cholesterol, serum calcium, feed consumption, and dietary cholecalciferol.

Hy-Line W36 hens, 20 wk of age, were randomly assigned to one of three dietary treatments consisting of cholecalciferol at (0, 550, or 2,750 IU/kg of finished feed). Serum calcium and cholesterol, yolk cholesterol, and egg specific gravity were measured. Feed consumption, egg production, and egg weight measurements were also recorded. Feed consumption, egg production, and egg weights were initially reduced when cholecalciferol was omitted from the diet. These effects disappeared by the beginning of the fourth 28-d period. Egg cholesterol concentrations among treatments followed no consistent pattern. A positive correlation was noted between serum calcium and serum cholesterol.

Effect of removing trace minerals from the diet of hens laying eggs with heavy or light shell weight.

Hy-Line W36 hens, 48-wk-old, were used to study the effect of removing either supplemental Fe, Cu, Zn, Mn, or all of them from the diet of hens laying eggs with heavy shell weight (HSW) or light shell weight (LSW). The experiment was conducted for 10 wk. Egg production (EP), egg mass (EM), feed consumption (FC), feed conversion efficiency (FE, grams feed:gram egg), egg weight (EW), shell weight (SW), percentage shell (PS), specific gravity (SG), percentage fertility, percentage hatchability of fertile eggs (HF), and percentage hatchability of total eggs set (HT) were measured. Removing trace minerals from the diet had no significant effect on EP, EM, FC, FE, EW, PS, SG, HF, or HT with either HSW or LSW hens. However, removing Mn from the diet significantly reduced SW with HSW hens. Diet by shell classes (HSW and LSW) interaction was not significant for any variable measured. The HSW hens had significantly higher EW, SW, PS, SG, and EM and lower EP, HF, and HT. However, there were no significant differences on FC or percentage fertility between the two groups of hens.

The utilization of sodium in sodium zeolite A by broilers.

Two identical experiments were conducted with 1-d-old broiler chicks to determine whether the Na in sodium zeolite A (SZA) was utilizable. Three male and three female chicks were randomly assigned to each of eight replicate pens per treatment. A corn-soybean meal basal diet was formulated to contain supplemental levels of 0, .02, .04, .06, .08, and .16% Na from either SZA or NaCl. The diets were isocaloric and isonitrogenous. The Cl level within each dietary Na level was kept constant. Feed and deionized water were offered for ad libitum consumption throughout each 21-d experiments. In both experiments, broiler body weight was increased with each addition of Na from either NaCl or SZA. In Experiment 1, the addition of Na, whether from NaCl or SZA, resulted in an improvement in feed consumption and feed conversion compared with birds fed the control diet. In Experiment 2, body weights of birds fed .04 to .08% Na from SZA were heavier than those fed the same levels from NaCl. Overall the addition of Na from SZA or NaCl resulted in an improvement in body weight, increased feed consumption, and improved feed conversion. Data from these experiments indicated that the Na in SZA was able to be utilized by broilers as efficiently as the Na from NaCl.

Response of broiler breeder females to feed restriction below recommended levels. 3. Characterizing the onset of sexual maturity.

The objective of this study was to characterize how the physical attributes associated with sexual maturity would be affected by feed allocation as female broiler breeders passed through the pullet-layer transition period. Treatments consisted of five feeding programs, or body weight goals, during the period of 0 to 20 wk of age. Those were 8% above breeder standard, standard (primary breeder recommended body weights), and 8, 16, and 24% below standard. The characteristics measured included body and fat pad weights, pubic spread, comb development, head score (comb and wattle appearance), shank length, total plasma lipid concentration, ovary weight, oviduct weight, bursa of Fabricius weight, and age at sexual maturity. The generalized effect of increased severity of the feed restriction programs was to delay the birds' development without altering their ultimate physiological values. The exceptions to this were relative body weight and shank length after maturity, which were reduced in the most severely restricted birds. Measurements of pubic spread and comb growth and subjective scores of head appearance would be useful and easily obtained information when estimating the progression of a flock toward sexual maturity.

Research note: effect of age on the yolk to albumen ratio in chicken eggs.

The effect of age on the yolk:albumen (Y:A) ratio was studied for eggs obtained from Hy-Line W36 and Arbor Acres hens. Albumen weight was more closely associated with egg weight (EW) than yolk weight for both commercial layers and broiler breeder hens. A small positive relationship between EW and Y:A ratio was found. A significant increase in Y:A ratio was evident in older flocks from both breeds.

Research note: a lack of response to pantothenic acid supplementation to a corn and soybean meal broiler diet.

Two 21-day battery studies were conducted to determine whether a corn and soybean meal diet without pantothenic acid supplementation was adequate for growth and feed efficiency of broilers. In each experiment, 64 1-day-old broiler chicks (32 male and 32 female) were assigned to each of six dietary treatments. The basal diet was supplemented with 0, .3, .6, 2.4, 4.8, and 14.4 mg of supplemental pantothenic acid/kg of diet. Each diet in both experiments was fed to eight pens containing four females and four male day-old Arbor Acres broiler chicks. The basal diet contained 22.3% protein and 4.74 mg/kg pantothenic acid by analysis. No improvement in growth or feed efficiency was obtained from any level of pantothenic acid supplementation.

The effects of dietary protein level on the reproductive performance of bobwhite hens.

Two experiments were conducted to evaluate the protein requirement of adult bobwhite quail. Flight-type quail were used in one experiment and meat-type quail in the other. Corn and soybean meal diets containing 12, 15, 18, 21, and 24% protein were fed. Increasing the protein level of the diet from 12 to 15% significantly increased egg production with the flight-type bird. However, only a nonsignificant increase in egg production was obtained with the meat-type birds when the protein level was increased to 15%. Higher levels of protein did not result in further increases in egg production in either strain. Increasing the protein from 12 to 18% (flight) or 21% (meat) resulted in increased egg weight. Egg mass of flight-type hens receiving 18 and 21% protein was significantly greater than egg mass from hens receiving 12 and 15% protein. Hatch of fertile eggs, hatch of total eggs, chick weight, or weight of adult birds were not affected by protein level. Feeding the 12% protein diet resulted in significantly reduced fertility in the flight-type birds but not in the meat-type birds.