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PubMed1982

Significance of body weight as a performance parameter.

The laying performance of different body weight classes, defined on both a genetic and phenotypic scale, were compared. The distribution of pedigreed Leghorn breeders of both sexes were truncated on the basis of 30 week body weight into two classes: light (L) or heavy (H). The progeny then were classified according to parental mating types as either L X L, L X H, or H X H. Differences among these progeny groups defined the genetic scale. The phenotypic scale was derived separately by phenotypic truncation of the progeny distribution into light (L), medium (M), and heavy (H) body weight classes at 30 weeks. Differences in rate of lay and in egg mass output between classes were in poor agreement with respect to the two scales. Light birds were poorest egg producers on the phenotypic scale but were the best egg producers on the genetic scale. Superior egg production by the heavy-bird class during the late spring and early summer months of the year could not be demonstrated. Deviations in body weight sharply reflected poorer performance on the phenotypic scale but not the genetic scale. This emphasizes the dominant role of management, feeding, and disease control over the genetic influence in maintaining optimum size for satisfactory productivity.

Animals↗

PubMed1975

[Studies on reducing the crude protein content of feeds fed to chicks and young hens (laying stock)].

2 rearing trials were carried out on a total of 8550 hybrid chicks (White Leghorn) to investigate in which way food mixtures containing reduced levels of crude protein (supplemented or unsupplemented with amino acids) might influence the growth of chicks and young hens. Decreases from 21.5% to 16.5% in the crude protein content of chicken feed and from 15% to 13% in feeds feed to young hens (greater than 8 weeks of life) did not reduce the live weight of birds at the end of the rearing period to any appreciable extent. No clearly defined differences were found to exist between the different types of feed tested concerning the amount of food and energy consumed per unit of weight gain and the mortality rate among the birds; it was shown, however, that the demand for crude protein per unit of weight gain was clearly reduced in birds reared at the lower crude protein level. For young hens receiving the diet poorer in protein the date when the birds began laying was slightly delayed. Otherwise, no statistically significant differences were found to exist between the young birds fed varying levels of crude protein, concerning the age at 50% laying performance and other parameters that are characteristic of the entire laying period (laying performance, weight of individual eggs, food consumption, mortality, fertilization of hatching eggs, hatchability of eggs). It appears that the feeding of a reduced protein diet to chicks and young hens (laying stock) did not have any detrimental effect on the growth and later laying performance of the birds. Apart from the fact that the demand for protein feeds is considerably reduced during the rearing period the costs of feeding per bird can also be cut down.

Animal Feed↗

PubMed1984

Influence of toe-clipping and stocking density on laying hen performance.

Three experiments were conducted to investigate the influence of toe-clipping and bird density on laying hen performance. Toe-clipping was done on day-old chicks by removal of the digital claws from the front toes. Toe-clipped (TC) and intact (IN) pullets were assigned randomly to laying cages (Experiments 1 and 2, 19 weeks of age) or housed in similar body weight groups (Experiment 3, 18 weeks of age) at caging densities of either 4 (465 cm2/hen) or 5 (372 cm2/hen) hens per cage. Experiment 3 body weight groups were: heavy (greater than or equal to 1475 g), medium (greater than or equal to 1375 g, but less than 1475 g), light (greater than or equal to 1275 g, but less than 1375 g), and extra light (less than 1275 g). Body weights were determined at various ages during the grow-out and egg-laying periods. Beginning at 22 weeks of age, average daily egg weight, feed consumption, feed conversion, hen-day egg production, and mortality measures were made for 12 periods of lay of 28 days each. In Experiments 1 and 2, IN pullets were consistently heavier throughout the grow-out period and consumed significantly more feed during the egg laying period than TC birds. Significantly greater average daily egg weights were found in IN than in TC hens in Experiment 1 but not in Experiment 2. Increasing the number of hens from 4 to 5 hens per cage resulted in a significant reduction in feed intake and body weight gain in Experiments 1, 2, and 3. In Experiment 1, mean daily egg weight was significantly increased (.11 g) upon crowding. In Experiment 2, crowding elevated mortality. In Experiments 1 and 2, but not 3, a significant toe treatment by bird density interaction was observed for hen-day egg production. The IN birds had lowered hen-day egg production rates when crowded than when they were afforded more space, whereas hen-day egg production was elevated in crowded TC hens when compared to TC hens housed at the less crowded density. In Experiment 3, an initial (4 weeks of age) significant depression in pullet body weight was found in the TC pullets but disappeared by the 8th week. Feed usage was also significantly greater in IN than in TC hens in Experiment 3. Toe treatment did not affect any other hen performance variable measured. Egg weight, feed intake, and feed conversion measures varied by body weight groups. In general, the heavier hens consumed more feed and laid heavier eggs, but they were less efficient in converting feed into eggs.

Animals↗

PubMed2003

Effects of high-tannin sorghum and bentonite on the performance of laying hens.

The effects of feeding high-tannin sorghum (HTS) (5% catechin equivalents (CE)) on the performance of laying hens were examined in two experiments. In experiment 1, the effects of including varying levels of HTS in layer diets were investigated. Sixty-three Isabrown hens were randomly assigned to each of the seven diets over a period of 56 days. In experiment 2, the effects of bentonite on the utilization of HTS (3.74% CE) by laying hens were investigated. Forty-five Isabrown hens were randomly assigned to each of five diets over a period of 42 days. In both experiments, weekly measurements were made for feed intake (FI), percent hen-house production (% HHP), egg weight and egg specific gravity (ESG). The results of experiment 1 showed that the different sorghum inclusion levels had no effect (p > 0.05) on HHP, egg weight and ESG, while those of experiment 2 showed that maize and LTS diets gave similar weight gain. FI and FE (p > 0.05). However, HHP was higher (p < 0.05) for the LTS diet than for the other diets. The addition of bentonite of 0.25% or 0.5% to the HTS diet did not improve (p > 0.05) layer performance. When all the results were considered together, it was concluded that HTS can be used in layer diets without adverse effects on performance. The use of bentonite to deactivate sorghum tannins is not considered necessary.

Animal Feed↗

PubMed2000

The effects of various dietary levels of phytase and available phosphorus on performance of laying hens.

Data previously obtained from our laboratory indicated that addition of 300 U of phytase/kg diet supported optimal long-term performance of laying hens (20 to 70 wk) fed a corn-soybean meal (SBM) diet containing 0.10% available phosphorus (AP). Our primary objective was to determine if a phytase level lower than 300 units/kg is adequate for a commercial strain of Single Comb White Leghorn laying hens (n = 504) fed a corn-SBM diet containing no supplemental P (0.10% AP). Dietary treatments consisted of the corn-SBM basal diet (0.10% AP, 3.8% Ca, and 17% CP) supplemented with 0, 100, 200, 250, or 300 U of phytase/kg, 0.05% inorganic P (0.15% AP), and a positive control diet containing 0.45% AP. Each of the seven dietary treatments was fed to six replicate groups of 12 hens from 20 to 60 wk of age. No significant differences in performance were observed among treatments during the first 8 wk of the experiment. By 28 wk of age, the 0.10% AP diet, with no supplemental phytase or P, resulted in significantly lower (P < 0.05) egg production and body weight compared with all other dietary treatments. Feed consumption, feed efficiency, and egg yield were subsequently depressed by 32 wk of age in hens fed the 0.10% AP diet. No other significant differences among treatments were observed for performance averaged over the entire 40-wk experimental period. The mean daily AP intake of hens fed the 0.15% AP, 0.45% AP, and 0.10% AP + phytase diets was 155, 474, and 103 mg, respectively. The results of this study indicate that phytase improves the utilization of P in corn-SBM diets for laying hens and that corn-SBM diets containing 0.10% AP + 100 units of phytase/kg diet or 0.15% AP supported egg production performance that was not significantly different (P > 0.05) from that of hens fed a corn-SBM diet containing 0.45% AP.

6-Phytase↗

PubMed1983

The effects of sorghum tannin and protein level on the performance of laying hens maintained in two temperature environments.

A study was conducted to investigate the effect of sorghum grain tannins on the performance of laying hens. A total of 144 White Leghorn hens were arrayed according to egg production during a 10-day preexperimental period into eight groups consisting of four nutritional treatments in each of two constant temperature environments (22 and 28 C). The nutritional treatments consisted of low (RS610) and high (Savanna) tannin sorghum grains compared isonitrogenously within a protein level at two protein levels (11.5 and 14.5%) in sorghum-soybean meal diets. These diets were fed for an experimental period of 6 weeks. Egg production and feed efficiency were reduced and weight loss was increased by 11.5% protein as compared with 14.5% protein. Tannin significantly reduced egg production and feed efficiency at both protein levels while egg specific gravity and shell thickness were adversely affected only at the lower level of protein. Egg weight and weight loss of hens were not affected by tannin. Except for weight loss, all parameters were slightly reduced by the higher temperature. At the end of the experiment, all hens were placed on a commercial laying ration for a 31-day period. Recovery from the treatment effects was evidenced by the similar egg production, body weight, egg weight, and shell characteristics among the previous treatments at the end of this period.

Animals↗

PubMed1987

Comparison of several induced molting methods on subsequent performance of single comb White Leghorn hens.

Seventy-two-week-old Single Comb White Leghorn hens were induced to molt by 11 different methods 1) to determine the utility of molt-inducing procedures that employ full feeding, limited feeding, and fasting and 2) to determine the postmolt performance of hens induced to molt by fasting to varying degrees of body weight reduction (BWR) then fed postfast, prelay (PF-PL) diets varying in nutrient density. Induced molt treatments were full feeding of 10 and 15% guar meal diets to 30% BWR; limited feeding by withholding feed to 30% BWR, except for 6-hr feeding periods on every 3rd, 4th, and 5th recurring day; fasting to 25, 30, or 35% BWR then feeding either a pullet developer ration or a fortified molt ration (FR) for 21 days. Egg production, egg weight, shell quality, Haugh unit, feed consumption, and mortality were recorded for 33 weeks. Molt treatments produced few significant differences; nonmolted control hens had overall poor performance. Full feeding of the 15% guar meal diet caused a slow cessation and reinitiation of lay with acceptable lay performance. The 10% guar meal diet reduced livability. All recurring day, limited-feeding treatments conserved feed during the first 35 days of molt induction. The 3rd and 5th recurring day-feeding treatments were particularly effective and had acceptable lay performance and feed efficiency. Neither level of BWR nor type of PF-PL diet significantly affected postmolt performance. The 30% BWR-FR induced-molt method produced superior (but not significantly) postmolt lay performance.

Animals↗

PubMed2002

Effect of dietary supplemental levels of vitamin A on the egg production and immune responses of heat-stressed laying hens.

Two experiments were conducted to evaluate the effect of vitamin A supplementation of a commercial layer diet on the laying performance and immune function of heat-stressed hens. In Experiment 1, two different levels of vitamin A supplementation (3,000 and 9,000 IU/kg) were used to investigate the laying performance and antibody titer against Newcastle disease virus (NDV) of heat-stressed hens. Results showed that the high level of vitamin A supplementation (9,000 IU/kg) had a beneficial effect on the feed intake and laying rate of heat-stressed hens (P < 0.05), compared with the control group (3,000 IU/kg). The antibody titers were not influenced by the level of vitamin A (P > 0.05). In Experiment 2, the effect of four levels of vitamin A (3,000, 6,000, 9,000, and 12,000 IU/kg) on the antibody titer to NDV and T lymphocyte proportion was studied. The experimental birds were exposed to a high temperature (31.5 C) 15 d after NDV vaccination (Treatment 1) or immediately (Treatment 2). The results showed that the egg weight was increased (P < 0.01) by the high levels of vitamin A supplementation (6,000 and 9,000 IU/kg), but feed intake, laying rate, and body weight loss were not (P > 0.05). In Treatment 1, vitamin A had no significant effect on antibody titers against NDV in normal or hot environments but increased (P < 0.01) the proportion of alpha-naphthyl acetate esterase (ANAE)-positive cells. Vitamin A supplementation had a significant effect on NDV antibody titer and ANAE-positive cell proportion in Treatment 2 (P < 0.01). The results of the present study suggested that vitamin A supplementation in commercial layer diets to layer chickens under heat stress was beneficial to laying performance and immune function.

Animal Feed↗

PubMed1994

Laying hen performance as influenced by protein intake to sixteen weeks of age and body weight at point of lay.

White Leghorn chicks were fed corn-soybean meal diets containing 20, 17, 14, and 11% protein, with similar levels of energy, from hatch to 16 wk of age. Body weights at 16 wk were similar for pullets fed the 20 and 17% protein diets, but were reduced by 11 and 27% for birds fed the 14 and 11% protein diets, respectively, as compared with the 20% protein diet. At 16 wk of age, all birds were placed on a common 17% protein laying diet. Pullets fed the 14 and 11% protein laying diets were slightly slower coming into production, however, by 28 wk of age egg production was similar for all four growing treatment groups and remained so until the end of the experiment. Average egg weight was similar for pullets fed the two higher levels of protein during the growing period and significantly lower for those pullets fed the 11% grower diet for all except the 28- and 32-wk periods. Pullets fed the 14% grower diet produced eggs with average weights significantly lower than those for the higher protein diets from 40 to 58 wk of age. Although the results might be interpreted as indicating that higher protein growing diets result in body protein reserves that subsequently enhance egg size, it is more likely that the pullets consuming lower protein diets produce smaller eggs because they have smaller body weights.

Age Factors↗

PubMed2001

Effects of mould and toxin contaminated barley on laying hens performance and health.

Moulded and mycotoxin containing barley was incorporated into the diets for laying hens to study the effects on performance and health. Health indicators were different blood plasma parameters and liver vitamin A and E levels. A total of 30 hens were fed 3 diets, one supplemented with 30% of toxin-free and two with differently moulded barley from 1997 and 1998 for 7 weeks. The moulded diets contained low to moderate concentrations of ochratoxin A, zearalenone, deoxynivalenol and nivalenol. Inclusion of mouldy barley in the diets had an adverse effect on feed intake, feed conversion, digestibility of nutrients, egg production and egg quality. Plasma alkaline phosphatase was increased and certain biochemical blood parameters (bilirubin, uric acid, chlorine, protein, albumin, vitamin A) were also higher or changed compared to control. The ochratoxin A contamination although relatively low could have contributed to some of these effects as well as reduced intake of feed. The higher mould contamination and an unidentified cell-toxic constituent in the diet containing barley from 1998 can probably also explain the more marked effects from this diet.

Animal Feed↗

PubMed2026

Dietary L-Tyrosine Sustains Egg Production and Quality by Modulating Promoter CpG Methylation, Gene Expression, and Hormone Profiles in Reproductive Signalling Pathways of Aged Laying Hens.

Managing prolactin (PRL)-mediated reproductive suppression is critical for maintaining egg production in commercial laying hens. L-tyrosine (TYR), a precursor of dopamine (DA), may counteract age-related reproductive decline by suppressing PRL, thereby sustaining productivity and egg quality in late-phase laying hens. The present study evaluated the effects of dietary L-tyrosine supplementation on laying performance, egg quality, reproductive hormone profiles, gene expression, and promoter CpG methylation in aged laying hens. A total of 180 Atak-S laying hens (71 weeks old) were randomly assigned to three dietary treatments, each with six replicates of 10 hens, and were fed a basal diet without L-tyrosine (control) or the basal diet supplemented with 0.5 g/kg (TYR0.5) or 1 g/kg (TYR1) L-tyrosine for 12 weeks. Hens in the TYR1 group exhibited higher hen-day egg production, improved feed conversion ratio, and significantly greater eggshell weight, shell thickness, Haugh unit, yolk index, and albumen index than the control group (p < 0.05). Dietary L-tyrosine increased plasma DA and serum estradiol while reducing serum PRL (p < 0.05). L-tyrosine also upregulated the expression of key dopaminergic and reproductive signalling genes, with corresponding promoter hypomethylation (p < 0.05), whereas PRL mRNA expression tended to decrease with concurrent promoter hypermethylation. A significant negative correlation was observed between target gene expression and promoter CpG methylation levels (p < 0.05). These findings indicate that dietary L-tyrosine modulates reproductive hormone profiles and molecular responses within reproductive signalling pathways, resulting in improved laying performance and egg quality. Therefore, L-tyrosine may represent a promising nutritional intervention to sustain reproductive function and productivity in late-phase laying hens.

Animals↗

PubMed1999

Performance of laying pullets fed on cereal-free diets based on maize offal, cassava peel and reject cashew nut meal.

1. A 70-d experiment was conducted to determine the response of 26-week-old laying pullets to cereal-free diets based on maize offal, cassava peel and full-fat cashew nut meal (CNM) in comparison with a standard 550 g maize/kg reference diet. The 4 test diets all contained 315 g CNM/kg 232.5, 155.0, 77.5 and 0.0 g/kg of maize offal in combination with 77.5, 155.0, 232.5 and 315.0 g/kg of cassava peel, respectively. 2. Pullets fed on the 4 CNM-based diets consumed (P<0.05) less food than those fed on the reference diet; they also had lower (P<0.05) rates of lay, produced less (P<0.05) egg mass, had lower (P<0.05) food conversion efficiencies and their eggs had a lighter (P<0.05) yolk colour. Pullets fed some of the CNM-based diets also gained more (P<0.05) weight, the heaviest (P<0.05) being birds reared on the diet containing 315 g/kg cassava peel. Egg weight, shell thickness and albumen height from all eggs were similar. Pullets fed on the CNM-based diets had inferior (P<0.05) retention of dry matter and protein. 4. It was concluded that feeding full-fat CNM allowed for high dietary inclusion rates of cassava peel and maize offal and the resultant diets, which contained no maize, supported satisfactory performance of laying hens.

Animal Feed↗

PubMed1989

Effect of dietary aluminum on calcium and phosphorus metabolism and performance of laying hens.

The effect was studied of feeding dietary Al as aluminum sulfate on calcium and phosphorus metabolism and performance of Single Comb White Leghorn laying hens. In Trial 1, graded levels of Al (0, .05, .10, or .15%) were added to a corn-soybean meal layer diet containing 3.3% Ca and .5% available P. Each diet was fed for 28 days to six groups of six individually caged hens. Adding .15% Al to the diet significantly (P less than .05) reduced feed intake, egg production, body weight, tibia breaking strength, and plasma inorganic P. In Trial 2, graded levels of Al (0, .1, .2, or .3%) were added to the basal diet. Each diet was fed to five or six individually caged hens for 42 days. Feeding .3% Al significantly (P less than .05) decreased plasma inorganic P in samples collected immediately following oviposition after 10 and 42 days of treatment. Plasma total Ca, tibia weight, and tibia breaking strength were unaffected by dietary treatments. Egg production and feed intake during Days 1 through 21, but not during Days 22 through 42, were significantly reduced by .3% Al. The results indicated that the addition of .3% Al to a laying hen diet has a negative effect on P metabolism and egg production.

Aluminum↗

PubMed1992

Effects of genetic strain and light management on the reproductive performance of turkeys.

The laying performance of six genetic strains of turkeys, which have been bred and maintained at the Ohio Agricultural Research and Development Center, Wooster, OH, was compared under three laying house lighting regimens over a period of 3 yr. Light Treatment 1 (L1) consisted of 14 h of continuous light (L) and 10 h of dark (D; 14L:10D) throughout the laying period. Treatment 2 (L2) consisted of 14 h of intermittent light (IL, 15 min L and 45 min D/h) followed by 10 h of continuous dark. The IL treatment was started following a period (6 wk) in which the hens were trained to use the trapnests. Thus, during the first 6 wk of their laying period, L2 hens were also provided 14L:10D. Treatment 3 (L3) hens were provided the same program as L1 for the first 14 wk of the laying period. They were then moved to a continuous period of 19L:5D for the remainder of the laying period. All eggs produced were recorded through 180 days after the first egg was laid. Traits studied included: the number of days to first egg after light stimulation; the number of eggs produced through 84, 120, and 180 days after the first egg was laid; the average clutch length; the maximum clutch length; the total days lost to broodiness; the rate of lay; and the effective length of the laying period. Highly significant differences (P less than or equal to .01) were observed among the strains used for all traits measured. Light treatments showed no significant effects on any trait measured. Thus, from the present studies, the delayed IL program provides an economically attractive management program for environmentally controlled turkey breeder houses.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1996

Influence of Trichoderma viride enzyme complex on nutrient utilization and performance of laying hens in diets with and without antibiotic supplementation.

The experiment was designed to test possible interactions of an enzyme complex (product from Trichoderma viride) and a feed antibiotic (flavophospholipol) in a barley diet on metabolism variables and egg production performance of Warren Brown laying hens. The basal diet contained 40% winter barley (French cultivar "Express", six row). The four treatments were as follows: O, control (without supplement); E, enzyme complex, 600 ppm; A, flavophospholipol, 10 ppm; EA, enzyme complex, 600 ppm and flavophospholipol, 10 ppm. The enzyme complex contained the following main activities: cellulase (10,500 U/g), endo-beta-(1:3)(1:4)-glucanase (24,000 U/g), and xylanase (32,000 U/g). The enzyme positively influenced AME content of the feed, organic matter (OM) utilization, and neutral detergent fiber (NDF) degradability (P < or = 0.01). When supplemented alone, the antibiotic had no influence on energy and nutrient utilization. No significant differences in egg production due to dietary treatments were observed. A significant enzyme by antibiotic interaction for AME (P < or = 0.01) and OM utilization (P < or = 0.001) as well as NDF degradability (P < or = 0.01) indicated a reduced enzyme effect in the diet containing antibiotic. Negative enzyme by antibiotic interaction for energy utilization in laying hens suggested that the positive response to dietary enzyme supplementation in the mature laying hen (Treatment O vs E) was to great extent mediated by the activity of intestinal microbes.

Animal Feed↗

PubMed1999

Effects of beta-mannanase in corn-soybean meal diets on laying hen performance.

Recently, a patented enzyme product (beta-Mannanase, Hemicell) has been shown to improve feed conversion in corn-soybean diets fed to broilers and swine. The mechanism of beta-Mannanase is to degrade beta-mannan, which is an antinutritional factor existing in many legumes, including soybean and canola meals. The objective of this study was to determine whether or not performance can be improved by including beta-Mannanase in diets of commercial laying hens, 18 through 66 wk of age. A 2 x 2 x 2 factorial arrangement of treatments was employed. There were two energy sequences of 2,926-2,907-2,885 and 2,827-2,808-2,786 kcal ME/kg, which changed at 33 and 43 wk of age respectively; two dietary enzyme levels (0 and 110 units/g); and two Hy-Line strains (W36 and W77). Hen-day production, hen-housed production, BW, feed intake, mortality, egg weight, and specific gravity data were collected biweekly. Data were analyzed in four cycles (each with six 2-wk periods) and also for the whole experiment. beta-Mannanase increased egg weight from 51.4 to 51.7 g/egg (P < 0.05) in the first 12-wk cycle. This effect was consistent across energy levels. beta-Mannanase significantly improved hen-day and hen-housed production after the first cycle. Hen-day production of the beta-Mannanase group was 0.70, 1.07, and 1.5% greater than the control for cycles two, three, and four, respectively (P < 0.01). After 30 wk of age, average hen-day production of hens fed the low-energy diets with beta-Mannanase was similar or superior to that of hens fed the high-energy diets without the enzyme. The study indicates that beta-Mannanase is capable of increasing egg weight in commercial layers at early stages of production, and increasing egg production, particularly delaying the postpeak decline in productivity.

Animals↗

PubMed1992

Comparison of behavior and performance of laying hens housed in battery cages and an aviary.

Experiments were carried out to study the behavior and production performance of hens housed in battery cages (3 birds x 112 cages) and an aviary (437 birds). Direct visual observations and videotapings of hen behavior were collected at 24 to 25, 36 to 37, 49 to 50, and 61 to 62 wk of age. Production data were collected daily. Stereotyped behaviors were much more frequent (P less than .01) in the battery cages (7.0 to 24.7%) than in the aviary (1.0 to 2.7%). Comfort behaviors were performed by aviary birds (3.9 to 5.5%) much more frequently (P less than .01) than by the caged birds (.7 to .9%). The birds were more active during a few hours before dark and just after light in both cages and the aviary. In both groups, the production performance of hens was similar and relatively high. The results of the current study indicate that aviaries provide a more comfortable environment for birds and almost the same productivity per bird as battery cages.

Age Factors↗

PubMed1992

Cholesterol concentration of egg yolk and blood plasma and performance of laying hens as influenced by dietary alpha-ketoisocaproic acid.

Experiments were conducted to determine the effect of supplemental alpha-ketoisocaproic acid (KIC) or Leu on layer performance and plasma and egg cholesterol levels. In the first experiment, 0, .09, or .27% KIC and .09 or .27% Leu were fed to 62-wk-old laying hens. In a second experiment, the same levels plus another level of .54% KIC and .54% Leu were fed to 32-wk-old hens for an 8-wk period. The basal diet or the basal diet supplemented with .27% KIC or .27% Leu were continued for 20 wk to determine the long-term effects of these supplements. In a third experiment, hens were fed 0, .1, .2, or .4% KIC for 8 wk. The addition of KIC and Leu to the hen diets did not affect percentage egg production, egg weight, shell thickness, or Haugh units. In Experiment 1, .27% KIC and .09% Leu significantly increased BW gain. Neither KIC or Leu significantly affected BW gain in Experiment 2 when measured at 8 or 28 wk. In the third experiment, diets supplemented with KIC increased significantly BW gain. In Experiment 1, .09% KIC and .09% Leu significantly reduced egg cholesterol at 4 wk. After 8 wk, .27% KIC reduced egg cholesterol significantly below the controls. No effect on plasma or egg cholesterol was observed in Experiments 2 and 3.

Animal Feed↗