[Show abstract][Hide abstract] ABSTRACT: Posthatched naive or inoculated male broiler chicks were kept in separate rooms. An inoculum was prepared from intestines of stunting-syndrome affected broiler chicks. Tap water was supplied from 2 L cups, 1 cup per pen. In the Ist experiment, the naive chicks were provided with tap water only and the inoculated ones had free access to tap water or to an electrolyte solution. In the 2nd experiment, the naive and inoculated birds had free access to water in addition to an electrolyte solution. Supplementation was provided up to 3 weeks of age; thereafter all chicks had access to tap water only. Water or electrolyte consumption and body weight (BW) were determined. Total water intake of inoculated chicks was higher than that of naive counterparts (P<0.001). Electrolyte supplementation increased drinking (P<0.001) in inoculated birds more than in naive ones. At 1 week old the weight of the inoculated birds was about 64% of the weight of naive ones; at the age of 4 and 6 weeks it was about 74% and 86% respectively. Compensatory growth was most apparent in the inoculated chicks provided with electrolyte solution. At the age of 6 weeks, the latter exceeded the BW of the exclusively water supplied counterparts by 327 g. Electrolyte supplementation up to the age of 3 weeks had no effect on the naive counterparts. Osmolality was reduced slightly, but very significantly by inoculation; electrolyte supply had no effect on this variable. Sodium concentration in the plasma was higher in the inoculated birds. Plasma albumin was markedly reduced by inoculation on weeks 1 and 2. Whereas the inoculated chicks supplied with electrolytes resumed the level plasma albumin level of the naive chicks on week 3, an over-compensation occurred in the inoculated-water-supplied (IW) group, and they surpassed the naive chicks significantly. Blood hematocrit increased significantly with age; inoculation, age and/or electrolyte supplementation had no effect on this variable. Sodium-dependent glucose transport rates were enhanced in vesicles obtained from inoculated chicks as compared to naive ones. While electrolyte supplementation had no effect on glucose active transport in naive chicks, electrolyte supplementation decreased rates of glucose active transport in inoculated ones. These data demonstrate that electrolyte supplementation during the early age may be used to enhance the tolerance of broiler chicks to stunting-syndrome by improving food and water consumption, and subsequently growth rate during and after cessation of electrolyte supply.
Full-text · Article · Sep 1999 · British Poultry Science
[Show abstract][Hide abstract] ABSTRACT: Infectious stunting syndrome (SS) in broilers is a multi-symptomatic disease that includes lesions in the intestinal tract. We investigated whether these lesions impeded functions of the intestinal immune system. Two functions were studied: the capacity to generate 1) immune responses to a resident pathogen .(E. coli) of the gut and to a parenterally administered antigen (ss-casein), and 2) tolerance to an orally administered antigen (ss-casein). SS was induced in day-old broilers by an inoculum prepared from SS afflicted broilers. After onset of SS, immune responses (or absence of, in the case of tolerance) were studied by specific antibody production and T lymphocyte proliferation. Immune responses were induced by subcutaneous immunization of broilers against ss-casein or following natural exposure to enteric .E. coli. Oral tolerance was induced by a single feeding of ss-casein in gelatine capsules. Both enterai anti-E. .coli and parenteral anti-ss-casein responses were significantly reduced in SS birds. SS afflicted broilers did not develop ss-casein-specific oral tolerance. These results indicate dysfunction of both the intestinal immune system and that of systemic acquired immune responses in SS.
[Show abstract][Hide abstract] ABSTRACT: Responses to stunting syndrome (SS) infective material obtained from affected broilers and administered per os were monitored for 3 wk in a fast-growing commercial broiler population, in slow-growing Leghorn chicks, and in turkey poults. At 2 and 3 wk, the size of the gastrointestinal tract (GIT) segments, the pH of the GIT contents, and the activities of digestive enzymes in the intestinal contents and of disaccharidases on the jejunum mucosae were determined. Inoculation affected the genetic stocks differently. In broiler chicks, growth and feed utilization were markedly reduced. In contrast, inoculation of Leghorns was accompanied by improved feed intake and growth rate. Performance of poults was affected only slightly, albeit significantly. The effect of inoculation on the pH of crop and intestinal contents in Leghorn chicks was opposite to that found in broiler chicks, i.e., a significant increase in the crop and small intestinal pH in the former vs a significant decrease in inoculated broilers. Although inoculation of the broiler chicks did not affect the pH in the proventriculus, in Leghorn chicks it was reduced by 25%. In poults, inoculation did not significantly affect GIT contents pH. The GIT segments were markedly enlarged in broiler chicks, whereas in Leghorn chicks the opposite trend was observed; namely, intestinal segment weights were significantly reduced. In poults, inoculation caused a reduction in the intestinal segments and gizzard weight at 3 wk. During this same period, the liver and pancreas relative weights were dramatically increased in broiler chicks. A higher relative heart weight at 2 wk was observed in broilers and poults; this trend persisted to Week 3 in poults but not in broiler chicks. In broiler chicks, a nonsignificant reduction was observed for all enzymes assayed at 3 wk and for chymotrypsin at 2 wk. In Leghorn chicks, inoculation was accompanied by a marked and significant increase in the activity of chymotrypsin during both periods. In poults, inoculation caused a marked increase in the activities of amylase during Week 2 and 3, and trypsin at 3 wk. Maltase and saccharase activities in the jejunum of broiler chicks were slightly depressed a t 2 and 3 wk, the depression being significant at 2 wk for maltase and at 3 wk for saccharase. In the Leghorn chicks, inoculation caused a twofold increase in the activities of both enzymes. As in Leghorns, inoculation of poults with SS infective material caused a marked increase in the activities of the disaccharidases. The different responses to SS inoculation in the different genetic stocks are discussed.
[Show abstract][Hide abstract] ABSTRACT: Chickens from three genetic stocks known to differ in growth potential consumed ad libitum either a single (control) diet or a choice of two diets that differed in protein and energy. Formulation of the choice diets was such that when mixed in specific proportions they provided single diets that decreased in protein and increased in energy over the experimental period. When comparisons of feeding regimens were made at a common age, body weights and feed efficiencies for all stocks were enhanced in chicks fed a single diet. When comparisons were made at a common body weight for controls, chickens fed the single diet were about 15% heavier than those given a dietary choice. For feed efficiency, however, the pattern remained for the faster growing stock whereas there was no difference between feeding regimens for the slower growing stock. Chicks provided a choice of diets had heavier abdominal fat pads and lighter breasts relative to body weight than those fed a single diet. With choice feeding, there were stock by diet interactions for dietary preferences through the first 9 d after hatch. Early on, the interactions resulted from the faster growing stocks exhibiting a greater preference for the diet higher in protein and lower in energy than the slower growing stock. By Day 5, however, the interaction occurred because stocks exhibited either no dietary preference or preferred the diet that was lower in protein and higher in energy. Regardless of genetic stock, at 9 d of age and thereafter there was a clear preference for the diet lower in protein and higher in energy than the diet higher in protein and lower in energy. These data for feed intake were consistent with behavioral observations that showed a preponderance of chicks eating from the feeder containing the diet lower in protein and higher in energy. Compared to a single diet, under choice feeding, energy utilization was negatively influenced more in the faster than slower growing stocks. Protein and sulfur amino acid utilization was not affected by feeding regimen in faster growing stocks, but was enhanced under choice feeding in the slower growing stock. Although lysine utilization was enhanced by choice feeding in all stocks, the effect was greater in the slower than in the faster growing ones. These data demonstrate that although broiler diets are formulated to enhance growth and overall feed efficiency, chicks that are provided a dietary choice of protein and energy do not eat to maximize growth or feed efficiency.
[Show abstract][Hide abstract] ABSTRACT: The effect of supplementing a cornsoybean diet (C) with glucose (G) or maltose (M) on young broilers (from hatch to 3 wk of age) affected by stunting syndrome (SS) was studied. Stunting syndrome was induced by orally administering an inoculum prepared from the intestines of SS broiler chicks. Relative to the M diet, the G diet improved growth and feed utilization and increased feed intake in naive (NA) control chickens. The C diet was intermediate in this respect. In contrast to the NA chickens, diet did not affect growth or feed utilization in SS chicks. Changes in the relative weights of the gastrointestinal tract segments were evident by 1 wk of age and hypertrophy of these segments persevered to 3 wk of age. Stunting syndrome infection was accompanied by a significant increase in pancreatic trypsin-specific activity during Weeks 1 and 2, and in chymotrypsin activity at 1 wk. During this time, amylase-specific activity was not affected. At 3 wk of age, the specific activities of amylase, trypsin, and chymotrypsin in the pancreas were lower in the inoculated vs control birds. Whereas no significant effect of SS was observed with activities of amylase in the intestinal contents, trypsin activity was higher in SS chicks at 1 wk, and that of chymotrypsin lower during Weeks 2 and 3. Relative to NA chicks, the maltase and saccharase activities of SS chicks were much lower during Week 1, but increased later on and were similar to NA chick values at 2 and 3 wk. Whereas the level of blood plasma proteins did not vary from 1 to 3 wk in the NA chicks, it increased gradually in SS chicks to a level that significantly exceeded that in their NA counterparts. Blood plasma glucose and triglyceride levels were slightly lower in the SS chicks (NS), and the blood plasma cholesterol level was significantly reduced during Week 2. Relative to NA chicks, SS infection caused a significant increase in plasma calcium during Weeks 2 and 3, accompanied by a significant reduction in blood plasma phosphorus at 2 wk only. No difference was observed in the blood plasma level of uric acid, which peaked in both treatments during Week 2, or in D-beta-hydroxybutyric acid level, which was quite stable during the experimental period. Stunting syndrome infection was accompanied by a dramatic increase in amylase and alkaline phosphatase activities in the blood plasma, and by a slight but significant decrease in activity of lactic dehydrogenase. Stunting syndrome was concluded to be an affliction not only of digestion but also of metabolism. The main depression in growth caused by SS inoculation is probably due to metabolic alterations beyond those of digestion and absorption.
[Show abstract][Hide abstract] ABSTRACT: This paper reviews the literature on the response of young domestic fowl to various food restriction patterns. Emphasis has been given to anatomical, endocrine and immunological factors and their interactions with the genetic background. Under restricted feeding (limitation of the amount or time of access to food) chickens learn quickly to ingest the allocated quantity of food within a short period of time. When exposed to a single sequence of food removal and restoration, body weight losses are reduced for non-adapted compared with adapted individuals, for light breeds compared with heavy breeds, and for older compared with younger chickens. Adaptation to food restriction includes increased capacity and slower evacuation of the gastrointestinal tract (mainly the storage organs) to increase the supply of nutrients during the periods of food deprivation; increased hepatic lipogenesis and glycogen synthesis during the feeding cycle; and decreased heat loss on days of food deprivation. Synthesis and secretion of digestive enzymes in response to intermittent feeding has been found to be population dependent and consistent with the hypothesis that the amount of intestinal chyme mediates the synthesis and excretion of digestive enzymes from the pancreas. Numerous hormones are directly or indirectly involved in the metabolic responses to food restriction. Hyperinsulinaemia, increased plasma levels of growth hormone, triiodothyronine, thyroxine and plasma prolactin have been observed after the reintroduction of full feeding. It is suggested that the altered hormonal environment induced by food restriction contributes to a metabolic situation that may enhance immunocompetence.
No preview · Article · Nov 1996 · World's Poultry Science Journal
[Show abstract][Hide abstract] ABSTRACT: 1. Immunoresponsiveness and disease resistance were measured in broiler males maintained on ad libitum feeding throughout or on alternate-day feeding. Alternate-day restrictions were started 1 and 2 d after hatch so that on any one day there were chicks fed and fasted. 2. Severity of response to E. coli challenge as measured by lesion scores, and mortality was greater for chicks fed ad libitum than those fed on alternate days. For chicks fed on alternate days, lesion scores were lower for those without access to feed for the 24-h period immediately after challenge. 3. Spleen weights, the indicator of response to marble spleen disease virus challenge, were higher for chicks fed ad libitum than those fed on alternate days. 4. Antibody response to sheep red blood cell antigen was not affected by feeding regimen. 5. Ratios of heterophils to lymphocytes were higher for chicks given access to feed for the previous 24-h period than for those fasted during the previous 24-h or those that had been fed ad libitum. 6. Results of this experiment suggest that for alternate-day feeding programs, vaccination be administered on the day that chicks are not fed.
No preview · Article · Oct 1996 · British Poultry Science
[Show abstract][Hide abstract] ABSTRACT: 1. Body weight, digestive organ weights, and activities of disaccharidases (maltase and saccharase) activities were determined from day of hatch to 21 d of age in meat- and egg-type chickens. Blood plasma was analysed for enzyme activities and metabolite concentration. 2. In meat-type chickens food intake and growth rate were about 3-fold those in egg-type chickens. Food efficiency was superior in meat-type chickens throughout the experimental period. 3. Meat-type chickens hatched with disaccharidase activities exceeding those found in their egg-type counterparts 2- to 5-fold. From 7 d of age on, this trend reversed, i.e. activity was much higher in egg-type than in meat-type chickens. 4. Blood plasma amylase activity increased gradually in meat-type chickens and was higher than in egg-type chickens to 14 d of age. No breed differences were observed for alkaline phosphatase or lactate dehydrogenase activities during the experimental period. 5. Blood plasma concentrations of total protein, albumin, glucose, and calcium, were lower in meat than in egg-type chickens.
No preview · Article · Jun 1996 · British Poultry Science
[Show abstract][Hide abstract] ABSTRACT: Intake and digestion of leaves of Quercus calliprinos, Pistacia lentiscus, and Ceratonia siliqua, with and without supplementation of various amounts of polyethylene glycol (PEG), were examined. The tannin contents in these species exerted a substantial negative effect on feed intake and digestion. The effects were species specific and related to tannin content. Once-daily Supplementation with PEG efficiently neutralized the negative effects of tannins. The amount of PEG needed to produce a maximal increase in feed intake was lower than the amount required to produce a maximal increase in digestibility. The intake of digestible crude protein and metabolizable energy was raised in PEG-supplemented animals from a submaintenance level to levels considerably exceeding the maintenance requirement of goats. The response was related to the tannin content of the plant. Keywords: Goats; tannins; polyethylene glycol; foliage digestibility
Full-text · Article · Jan 1996 · Journal of Agricultural and Food Chemistry
[Show abstract][Hide abstract] ABSTRACT: Day-old male, meat-type chicks raised in brooder batteries were infected by orally administering an inoculum prepared from intestines of broiler chicks infected with stunting syndrome (SS). Naive controls were kept in a parallel room. The chicks were fed a commercial starter diet supplemented with two levels of enzyme preparations to 14 d of age. The experiment was continued to the age of 6 wk in order to estimate compensatory feed intake and growth. In a parallel study, digestibility of the feed was determined from 1 to 3 wk of age with control or inoculated chicks. The enzymes amylase and proteases were produced by Bacillus subtilis and Penicillium emersonii. Enzyme supplementation had no effect on feed intake, growth, or feed utilization, or on digestibility of fat, starch, protein, or energy. Because enzyme supplementation did not consistently affect performance of chicks and no interactions were observed between enzyme supplementation and infection status, data are presented for effects of infection only. Inoculation of SS-infective material reduced performance to 4 wk. Compensatory growth and feed intake were observed from the age of 4 wk onward. At the age of 6 wk the slight retardation of the inoculated chicks was not significant. On Week 1, retention of fat, starch, protein, and energy was significantly depressed in the inoculated chicks. At the age of 2 wk, retention of starch was not depressed, and at the age of 3 wk, the only consistent depression was that observed for fat. The proventriculus weight and content were consistently higher in inoculated chicks, as were the small intestine and intestinal content. The pH of the gizzard content was higher, and that of the small intestine content was lower, in the inoculated birds than in their control counterparts. Stunting syndrome infection was accompanied by a significant depression of trypsin activity in the pancreas at the age of 1 and 2 wk. At these periods, amylase and chymotrypsin were not affected. At 6 wk of age, the activities of amylase, trypsin, and chymotrypsin in the pancreas were higher in the inoculated than in the control birds. In the intestinal chime, amylase, trypsin, and chymotrypsin activities were lower in the inoculated birds on Week 1 and 2 (NS for amylase on Week 1). On Week 6, the activity of all enzymes assayed was higher in the inoculated birds (NS for amylase). It is suggested that the main factors depressing feed intake and growth in SS-infected birds are most probably beyond those of digestion.
[Show abstract][Hide abstract] ABSTRACT: The effect of dietary protein on growth, feed intake and efficiency, abdominal fat deposition, and breast meat yield was investigated
in broiler males from a commercial stock (WI) and from experimental stocks selected for low (LF) or high (HF) abdominal fat.
All birds were kept at constant high ambient temperature (32 C) and were provided with low- (LP) or high-protein (HP) diets
from hatch until 8 wk of age (Experiment 1) or from 4 to 8 wk of age (Experiment 2). In both experiments, HP diet significantly
increased 4- to 8-wk BW gain in the LF and HF stocks but reduced it in the WI stock as compared with the LP diet. Abdominal
fat, as percentage of BW, was almost twofold higher in the HF birds than in the LF ones, with WI mean being intermediate.
In contrast to the HF and WI birds, in which abdominal fat decreased with increased protein intake, abdominal fat was not
affected by dietary protein in the LF stock. The HP diet substantially increased breast meat yield in LF birds but not in
the WI birds, with HF birds exhibiting intermediate increase in breast meat weight. It was concluded that birds of varied
inherent growth rate and tendencies toward protein and fat deposition respond differently to dietary protein level under heat
[Show abstract][Hide abstract] ABSTRACT: Three experiments were conducted to study the effect of particle size obtained by grinding wheat and sorghum in a hammer mill
(HM) or roller mill (RM) on broiler performance. Broilers were fed a mash diet or crumbles to 4 wk of age, then pellets to
7 wk of age. When fed as a mash, diets produced with RM-ground grain improved performance. The effect of grinding was additive
to that of pelleting. The interactive effects observed between grinding method and the form of the feed on body weight and
feed intake were explained by the higher response to pelleting when grains were ground in HM vs RM. The positive effect of
grinding in RM on feed utilization was found to be additive to that of pelleting in all three experiments. The response of
females to feed texture was less pronounced than that of males. In males, feeding pellets vs mash increased mortality due
to ascites threefold, whereas grinding method had no effect. Females were less susceptible to ascites than males, and feed
texture had no effect in this respect. The effects of grinding and pelleting on the gastrointestinal tract segments were additive.
The main effects of feed texture were a significant increase in stomach weight and that of its contents following HM grinding
and a decrease in these following pelleting, with no interactions between the two.
[Show abstract][Hide abstract] ABSTRACT: Day-old male meat-type chicks were fed a commercial starter diet supplemented with 2 levels of enzyme preparations containing amylase and proteases up to 14 d of age. Enzyme supplementation had no significant effect on feed intake or growth rate, and was accompanied by a significant decrease in gizzard content and small intestine weight. The intestine contents increased and this increase was accompanied by a significant decrease in its pH. Enzyme supplementation depressed the activity of chymotrypsin in the pancreas and the activity of amylase, trypsin and chymotrypsin in the intestinal contents. Some carry-over effects were observed on d 42, 4 weeks after the cessation of the enzyme supplements. These were mainly a significant depression in the activity of trypsin in the intestinal contents. In a balance study, diets supplemented with 0,250 and 1,000 micrograms/kg enzyme preparations were supplied. Exogenous enzyme supplements had no significant effect on the digestibility of all the nutrients studied except for the highest level of enzyme supplementation, which improved slightly but consistently the digestibility of amino acids. Some age effects were observed, mainly a decrease in the digestibility of fat and starch, and in the ME of the diet from weeks 1 to 2 followed by an increase during week 3. Protein digestibility and retention of nitrogen decreased with age.
Preview · Article · Feb 1995 · Reproduction Nutrition Development
[Show abstract][Hide abstract] ABSTRACT: The effect of stunting syndrome (SS) on young broilers induced by orally administering an inoculum prepared from intestines of SS-affected broiler chicks was studied in two experiments. Depression of growth, feed intake, and feed utilization, respectively, was negatively related to the age of inoculation, i.e., highest at posthatch inoculation (63, 57, and 61%), and intermediate at the ages of 3 (42, 45, and 50%) and 7 d (29, 34, and 53%), whereas at the age of 14 d inoculation was ineffectual and the inoculated chicks performed similarly to the naive controls. Eating behavior was determined by periodically recording the number of chicks in each treatment group exhibiting this behavior, i.e., pecking mash in the feeder or pecking the litter. Eating activity was much higher in inoculated chicks (about 20 to 24%) than in the naive controls (6 to 12%) and as with performance negatively related to the age of inoculation. In chicks inoculated at the age of 14 d, eating activity was quite similar to that of the naive control chicks. Noninoculated chickens raised in the same room as their inoculated counterparts were infected by the disease agents. In some respects the consequences of horizontal infection were similar to those observed in inoculated chicks, i.e., depressed feed intake, growth, and feed utilization and a heavier heart, crop, proventriculus, gizzard, intestine, and gastrointestinal contents. In contrast, the activities of the pancreatic digestive enzymes were more similar to those of the naive controls than to those of the inoculated groups. At the age of 14 d, activities of amylase, trypsin, chymotrypsin, and lipase in the pancreas were lower in the inoculated than in the naive control birds. At the age of 21 d, the results were reversed and activity in the inoculated birds was higher than in the naive control birds. During both periods, the activity of pancreatic lipase was higher in the naive controls than in the inoculated birds. The hyperactivity estimated via a determination of eating activity suggests that SS is an affliction not only of digestion but also of metabolism.
[Show abstract][Hide abstract] ABSTRACT: 1. In an attempt to quantify the effects of "degree" of pelleting, two experiments were conducted. Diets were prepared by mixing together a mash composed mainly of maize (experiment 1) or sorghum (experiment 2) with soft pellets, or soft pellets mixed with hard pellets. 2. The pelleting degrees (PDs) were as follows: 0 mash; 0.5 mixture of soft pellets and mash 1 to 1; 1 soft pellets pelleted once; 1.5 mixture of soft and hard pellets 1 to 1; 2 hard pellets pelleted twice. 3. In experiment 2, the weight and length of the digestive organs were determined as well as digestive enzyme activities. In both experiments, the behaviour recorded was eating, standing, sitting and drinking. 4. Food intake and body weight gain were related to the degree of pelleting in a curvilinear manner. PD had a positive effect up to a peak (1 to 1.5 PD), after which its effect decreased. Food efficiency was not related to PD. In experiment 1, food efficiency of PDs 1 to 2 were superior to PDs 0 to 0.5 and in experiment 2, PDs 1.5 to 2 were superior to PD 0. 5. The relative weight of the gizzard was reduced by pelleting, whereas pelleting increased the relative weight of abdominal fat. The content of the crop was not affected by PD, whereas that of the proventriculus was lowest in the PD 2 group. Gizzard content was inversely related to PD. Pelleting reduced the length of the jejunum and ileum: which were shortened by about 15% with PDs 1 to 2, as compared to PD 0. The weight/length ratio of the jejunum and ileum tended to increase with increasing PD to a peak at PD 1.5, and to decrease thereafter. 6. Trypsin activity in the pancreas and amylase activity in the intestinal content were reduced by pelleting. 7. Chicks fed pelleted diets were less active: they 'sat' more and spent less time eating than their mash-fed counterparts.
No preview · Article · Oct 1994 · British Poultry Science
[Show abstract][Hide abstract] ABSTRACT: Diets were prepared with corn, wheat, or sorghum ground in a hammer mill and sieved to obtain coarse, medium, and fine particle size fractions. Their effect on broiler performance from hatch to 7 d and from 7 to 21 d of age was studied. The effect of particle size on the size and pH of the gastrointestinal organs was also determined. The three textures obtained for each grain were uniform in geometric mean diameter (GMD) and geometric standard deviation (GSD). Grain by texture interactions were not significant. Independent of grain source, the best performance was obtained with diets prepared from the medium texture. In these diets, the GMD of the grains varied from 1.13 to 1.23 mm and the GSD from 1.19 to 1.35. The fine fraction (GMD .57 to .67 mm) resulted in the lowest performance and that resulting from the coarse fraction (GMD 2.01 to 2.10 mm) was intermediate. At 7 and 21 d of age, gizzard weight and content were positively related to particle size. At the age of 21 d, duodenum weight and content was highest in chicks fed the fine diets. The pH of the gizzard content decreased with increasing grain particle size, whereas that of the small intestinal content increased. Some grain effects were also observed on the gastrointestinal tract. Gizzard weight was greatest in the cornfed birds. Wheat-fed chicks had the heavier intestines and contents. After overnight feed deprivation, feed consumption by 7-d-old chicks was related to the particle size during the first 2 h of refeeding, with greater intake of medium and coarse grains.
[Show abstract][Hide abstract] ABSTRACT: The effect of 3-day-old 'guides' of broiler or White Leghorn type chickens on posthatch behaviour (eating, drinking, standing and sitting), growth rate and livability was measured in broiler and Leghorn type chickens. Four trials were conducted. One trial was in cages and three were on a litter floor. Although the guides did not influence the behaviour of either breed in cages, growth of the broilers, but not of Leghorns, was depressed by the presence of broiler guides. In floor experiments, the presence of guides of both breeds increased ingestive behaviour (eating and drinking), with reduced growth of broilers reared with broiler guides, consistent with that observed in cages. Whereas in unstressed chickens vitality was not affected by the guides, cold stressing of Leghorn chickens in the hatcher most markedly increased the positive effect of the guides on ingestive behaviour, vitality and growth rate. Responses of the posthatched chickens to 3-day-old guides were dependent on housing, management, genetic breed and stressful settings.
No preview · Article · May 1994 · Applied Animal Behaviour Science
[Show abstract][Hide abstract] ABSTRACT: PGE2 was shown to play an essential role in the gonado-inhibiting effect of melatonin in Syrian hamsters by transforming the neuroendocrine signal to gonadal reactivity. Prostaglandin is a vital link in the transduction of photoperiodic information into gonadal function and the difference in its levels brought about by melatonin given at different times of the day could explain the phenomenon why gonadal involution occurs only upon administration of melatonin towards the end of the day. It appears also that the melatonin signal is decoded in the pituitary, probably involving the short loop negative feedback of LH on LH-RH hormones.
No preview · Article · Feb 1994 · Journal of Neural Transmission
[Show abstract][Hide abstract] ABSTRACT: The effect of diets prepared with corn ground in a hammer mill and sieved to obtain "coarse", "medium", and "fine" particle size fractions, on broiler performance from hatch to 7 d and from 7 to 21 d of age was studied. Five diets differing in geometric mean diameter (GMD) or geometric standard deviation (GSD) were assayed. The best performance in both age groups studied was obtained with the diet prepared from medium corn. In this diet the GMD was .769 mm, quite similar to those of two other diets (GMD .793 and .706 obtained by mixing the original corn with 18 or 36% "fine" fraction) with which lower performance was obtained. The uniformity of the particle size (described by the GSD) also had a positive effect on performance. The improved performance obtained with the diet containing the medium corn particle size could be partly attributed to lower GSD, which was 1.63 vs about 2.00 in the other diets.