Effect of early nutrient restriction on broiler chickens. 2. Performance and digestive enzyme activities.

An experiment was conducted to determine the effect of two early nutrient restriction programs on performance, selected characteristics of the gastrointestinal tract (GIT), and activities of digestive enzymes of broiler chickens. Three hundred and sixty male broiler (Ross x Ross) chicks kept in floor pens were assigned to three groups. The control group (C) was given ad libitum access to feed from 1 to 48 d of age. Another group was restricted from 11 to 14 d (R4) of age to an energy intake of .74 x BW.67 kcal ME/d, and a third group was restricted from 7 to 14 d (R7) of age to an energy intake of 1.5 x BW.67 kcal ME/d. Then, both restricted groups were given ad libitum access to feed through 48 d. Body weight and feed intake were determined weekly and selected carcass characteristics were measured at 48 d of age. Broilers also were sampled at 7, 14, 21, and 42 d of age to obtain data on components of the GIT (proventriculus, gizzard, pancreas, and small intestine) and activities of selected digestive enzymes. Feed-restricted groups were lighter in body weight (P < .01) at 14 and 48 d of age than the C group but were superior in overall feed efficiency. No treatment effects were observed for percentage yields of breast meat and abdominal fat pad. Absolute weights of GIT components were significantly reduced at 14 d of age by feed restriction. However, GIT components increased in weight more quickly after refeeding than did the whole body. Restricted groups had reduced (P < .01) specific activities of jejunal alkaline phosphatase and pancreatic trypsin, amylase, and lipase as compared with the C group at 14 d of age but not at 21 and 42 d of age. Relative activities for jejunal maltase and sucrase were greater (P < .01) at 21 d of age in the R4 and R7 groups than in the C group. The present data show that feed restriction results in transient changes in organs and activities of digestive enzymes, suggesting a functional adaptation to feed restriction.

Effects of early immune stress and changes in dietary metabolizable energy on the development of newly hatched turkeys. 1. Growth and nutrient utilization.

Two experiments were conducted to document the effects of an early immunologic stress and changes in dietary ME(n) on growth and nutrient utilization of newly hatched turkeys. Treatments in both experiments consisted of a complete factorial arrangement of two types of injection and four isonitrogenous diets. Turkeys were injected i.p. with saline (SAL) or a solution of lipopolysaccharide (LPS) (100 micrograms LPS/mL SAL) at 1, 3, and 5 d of age. In Experiment 1, two diets were formulated to contain 2,800 kcal ME(n)/kg. One was a corn-soybean meal-based diet (CSBM) and the other contained 8% Solkafloc (SKF). A third diet (3,100 kcal ME(n)/kg) was formulated by substituting 8% sucrose (SUC) for the 8% SKF. The fourth diet included in Experiment 1 was formulated to contain 3,700 kcal ME(n)/kg. The CSBM and SUC diets were also included in Experiment 2. Two additional diets tested in Experiment 2 were the CSBM diet containing 74.5 mg ibuprofen/kg (IBU) and a corn-soybean meal-based diet with a ME(n) value of 3,100 kcal/kg (CS31). Injection with LPS reduced (P < .05) BW of turkeys throughout Experiment 1 and until 9 d of age in Experiment 2, as compared with injection with SAL, irrespective of dietary treatment. The reduction in BW was mainly due to a decrease in feed intake (FI) (P < .05). Turkeys fed diets with 3,100 kcal ME(n)/kg were heavier (P < .05) than those fed diets with 2,800 kcal ME(n)/kg, irrespective of injection. Inclusion of ibuprofen to the CSBM diet from 1 to 14 d improved (P < .05) BW and feed efficiency (P < .01) of turkeys at 14 d of age, compared with turkeys fed the CSBM diet. Determined ME(n) was not affected by LPS injection. Adverse effects of LPS injection on growth of turkey poults were mainly the consequence of a reduced FI and not of altered nutrient utilization. These effects were not fully alleviated by feeding a diet with 3,100 kcal ME(n)/kg.

Effects of early immune stress and changes in dietary metabolizable energy on the development of newly hatched turkeys. 2. Selected characteristics of immune function.

Two 21-d experiments were conducted to document the effects of an early immunologic stress and changes in dietary ME(n) on selected characteristics of immune function of newly hatched turkeys. Eight treatments were included in each experiment. Treatments were the result of complete factorial arrangements of two types of injection and four isonitrogenous diets. Turkeys in both experiments were injected i.p. with .5, .5, and .2 mL of saline (SAL) or .5, .5, and .2 mL of a solution of Escherichia coli lipopolysaccharide (LPS) (100 micrograms LPS/mL SAL) at 1, 3, and 5 d of age, respectively. In Experiment 1, two diets were formulated to contain 2,800 kcal ME(n)/kg. One was a corn-soybean meal based diet (CSBM) and the other contained 8% Solkafloc (SKF). A third diet (3,100 kcal ME(n)/kg) was formulated by substituting 8% sucrose (SUC) for the 8% SKF. The fourth diet (HE) included in Experiment 1 was formulated to contain 3,700 kcal ME(n)/kg. The CSBM and SUC diets and two additional diets were tested in Experiment 2. The latter were the CSBM diet containing 74.5 mg ibuprofen/kg (IBU) and a corn-soybean meal diet formulated to contain 3,100 kcal ME(n)/kg (CS31). Concentrations of plasma IgG and jejunal IgG and IgA were not affected by injection or diet. Age-related changes in Ig concentrations were consistently observed in Experiments 1 and 2. Injection with LPS reduced the number or responses of blood leukocytes to mitogens at 8 d of age (P < .01), as compared with samples from turkeys injected with SAL. Leukocytes in whole blood samples from turkeys fed the HE diet responded less to LPS stimulation than those fed the SUC diet (P < .01). Injection with LPS did not markedly affect the characteristics of immune function studied, and feeding a diet with 3,100 kcal ME(n)/kg and 28.5% crude protein did not measurably affect the characteristics of immune function of young turkeys.

Effect of early nutrient restriction on broiler chickens. 1. Performance and development of the gastrointestinal tract.

An experiment was conducted to determine the effects of early nutrient restriction on performance and development of the gastrointestinal tract of broiler chickens. Four hundred male broiler (Ross x Ross) chicks raised in floor pens were assigned to two treatment groups. One group was given ad libitum access to feed from 1 to 48 d of age. The second group was feed restricted from 7 to 14 d of age to an energy intake of 1.5 x BW.67 kcal ME/d and then given ad libitum access to feed from 14 to 48 d. Body weight and feed intake were determined weekly. At 49 d of age, birds were processed for carcass yield, abdominal fat pad measurement, and body composition analysis. Broilers were also sampled at 7, 14, 21, and 41 d of age for proventriculus, gizzard, small intestine (duodenum, jejunum, and ileum), pancreas, and liver weights and for intestinal length measurements. Total DNA, protein:DNA, and RNA:DNA ratios of livers and jejuna were determined as indexes of changes in cell size and number. Feed-restricted broilers failed to catch up to the Control birds in BW at 48 d of age but were superior (P < .01) in overall feed efficiency. No treatment effects were observed on breast meat yields or abdominal fat. Moreover, percentage carcass fat, crude protein, ash, and dry matter were not affected by restricted feeding. Body weight and weights of gastrointestinal organs were reduced (P < .01) by feed restriction at 14 d of age. Restricted feeding, however, did not decrease the relative weights of organs, except for liver. Feed restriction also resulted in a reduction (P < .01) of liver cell number and size and a decrease in jejunum cell number. All organs recovered normal weight on refeeding, and all cellular constituent ratios (e.g., RNA:DNA, RNA:protein, and protein:DNA) returned to normal by 41 d of age. Absolute and relative weights of supply organs (e.g., proventriculus, gizzard, small intestine, liver, and pancreas) were less affected by feed restriction and responded more quickly to refeeding than the whole body.

Research note: vitamin E status of turkey poults as influenced by different dietary vitamin E sources, a bile salt, and an antioxidant.

An experiment was conducted to determine the effects of level and chemical form of dietary vitamin E on alpha-tocopherol status of poults. The effects of a dietary bile salt and an antioxidant on concentrations of alpha-tocopherol in serum and liver were also tested. Six dietary treatments were obtained by supplementing a corn-soybean meal diet with 12 IU of DL-alpha-tocopheryl acetate (TA)/kg (LE), 12 IU of TA plus 800 mg of sodium taurocholate/kg (LB), 12 IU of TA plus 500 mg of ethoxyquin/kg (LS), 12 IU of D-alpha-tocopheryl polyethylene glycol 1,000 succinate (TPGS)/kg (LT), 100 IU of TA/kg (HE), and 100 IU of TPGS/kg (HT). Growth rate and feed efficiency of poults were unaffected (P > .05) by dietary treatments. The HE diet increased alpha-tocopherol in liver (P < .01) at 14 and 21 days of age. Liver and serum alpha-tocopherol concentrations were unaffected by dietary TPGS (LT and HT diets) at any age. Serum alpha-tocopherol concentration was unaffected by dietary treatments at 5 days of age. The HE diet, however, increased (P < .01) serum alpha-tocopherol at 9, 14, and 21 days of age. Age-related changes in alpha-tocopherol concentration were observed. Both liver and serum alpha-tocopherol decreased markedly from 1 to 14 days of age. The HE diet only partly alleviated the reduction of alpha-tocopherol in liver and serum. The water-soluble form of vitamin E, TPGS, dietary sodium taurocholate, or dietary ethoxyquin, did not prevent the marked decline in alpha-tocopherol concentration of liver and serum during the 21-day experiment.

Posthatching changes in the immunoglobulin A concentration in the jejunum and bile of turkeys.

An experiment was conducted to document the age-related changes in IgA concentration in the small intestine of newly hatched turkey poults reared in floor pens and to determine whether infection with stunting syndrome (SS) affects age-related changes. Day-old turkey poults were dose per os with .5 mL of saline carrier (control) or with .5 mL of one of two dilutions (250- or 2.5 x 10(6)-fold) of a "crude" SS-causing inoculum. Inoculation with the 250-fold dilution depressed body weight gain (P less than .01) throughout the experiment and impaired feed efficiency (P less than .05) at 5 and 9 days of age as compared with the control group. After 9 days of age, all inoculated poults utilized feed more efficiently than did control poults (P less than .01). Stunting syndrome did not affect IgA concentrations in either bile or jejunum at any specific age. Age-related changes in IgA concentrations, however, were observed. Bile IgA decreased from 1 to 9 days of age, and then increased until 29 days of age. The IgA concentration in jejunal tissue increased linearly from 1 to 29 days of age (P less than .01), whether expressed as IgA concentration per gram of wet tissue or as percentage of total protein in jejunum. Age-related changes in IgA concentration in both bile and jejunum suggest that the secretory immune system associated with the digestive mucosa is not fully developed at the time of hatch.

Developmental patterns of selected characteristics of the gastrointestinal tract of young turkeys.

Developing embryos and hatchling poults were sampled (n = 4) at Days 22, 24, 26, and 28 of incubation and at 1, 2, 4, 6, and 8 days after hatching, and selected characteristics of the gastrointestinal tract (GIT) were measured. Body weight increased linearly up to day of hatching and also from 2 to 8 days posthatching. Residual yolk weight decreased rapidly starting on Day 26 of incubation and was nearly depleted by 4 days posthatching. Changes in weight of segments of the GIT nearly paralleled the increase in body weight until day of hatching. Thereafter, weights of the proventriculus, small intestine, and pancreas increased more rapidly than body weight until 6 days after hatching. At this time, change in weight of small intestine and pancreas seemed to parallel that of body weight, whereas proventriculus weight continued to increase more rapidly. Gizzard weight, as a percentage of body weight, increased until Day 4 posthatching and then remained relatively constant through 8 days. Specific activities (SA) of pancreatic amylase, lipase, and trypsin were low until after hatching. Subsequently, amylase SA increased nearly threefold by Day 6. Lipase SA remained nearly constant between Days 1 and 8, and trypsin SA increased only slightly. Total activities of pancreatic enzymes, however, increased substantially after hatching, mainly because of increased pancreas weight. Jejunal maltase SA was high at hatching but decreased markedly by Day 4. This decrease in SA resulted in a notable reduction in total maltase activity of the jejunum despite an increase in jejunum weight.