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PubMed1996

Effects of individual vs group penning on the performance of weanling pigs.

Two experiments (five trials) were conducted to determine the effects of individual vs group penning on the performance of 4-wk-old crossbred barrows and gilts. In each experiment, half the pigs were tested in a group pen (four pigs) for two 7-d periods and individually for one 7-d period and the other pigs were fed individually for two periods and as a group for one period. In Exp. 1 (two trials, each with five replicates of eight pigs), individually penned pigs had physical and visual contact with pigs in the adjoining pens; in Exp. 2 (three trials, each with five replicates of eight pigs), such contact was denied. Growth rate, feed intake, and feed efficiency were determined at the end of each period. In addition, during Trial 3 of Exp. 2 blood samples were collected at the end of each period and plasma was assayed for cortisol and triiodothyronine (T3) concentrations. Penning sequences produced inconsistent weight gains and feed intake. Differences in gain favored (P < .04) the individually penned pigs during Trial 3 of Exp. 2 and differences in feed intake favored the individually penned pigs during Trial 2 of Exp. 1 (P < .009) and during Trials 2 and 3 of Exp. 2 (P < .02 and P < .009, respectively). Penning treatment had no effect on feed efficiency, plasma cortisol, or T3 concentrations. These data suggest that pigs perform equally well whether fed and housed individually or in groups, with no indications of stress associated with individual pens and isolation.

Aging↗

PubMed2006

Dietary cholecalciferol and phosphorus influence intestinal mucosa phytase activity in broiler chicks.

1. The role of cholecalciferol and phosphorus in the regulation of intestinal mucosa phytase was investigated in broiler chicks. 2. A total of 144 7-d-old male broiler chicks were grouped by weight into 6 blocks of 4 cages with 6 broiler chicks per cage. Four maize-soybean meal-based mash diets were randomly assigned to cages within each block. The 4 diets consisted of cholecalciferol at 0 or 75 microg/kg and total phosphorus at 3.6 or 7.0 g/kg in a 2 x 2 factorial arrangement. The birds were given the experimental diets for 12 d under conditions which excluded ultraviolet light. 3. Broiler chicks fed on diets with the higher concentration of cholecalciferol had higher Vmax and Km of the mucosa phytase, weight gain, feed intake, feed efficiency and percentage tibia ash, higher ileal digestibility of dry matter, energy, phosphorus (P) and calcium (Ca), and increased retention of dry matter, nitrogen, P, Ca and energy. 4. Broiler chicks receiving diets with the higher P concentration showed lower Vmax and Km of the intestinal mucosa phytase but greater weight gain, feed intake, feed efficiency and percentage tibia ash, higher ileal digestibility of dry matter, energy, P and nitrogen, and increased retention of dry matter, energy, nitrogen and Ca. 5. In conclusion, both dietary P and cholecalciferol influenced the activity of intestinal mucosa phytase.

6-Phytase↗

PubMed2004

The efficacy of an Escherichia coli-derived phytase preparation.

Five experiments were conducted to evaluate the effect of an Escherichia coli-derived phytase on phytate-P use and growth performance by young pigs. The first experiment involved time course, pH dependence, and phytase activity studies to investigate the in vitro release of P from corn, soybean meal, and an inorganic P-unsupplemented corn-soybean meal negative control diet. In Exp. 2, which was designed to determine the efficacy of the E. coli-derived vs. fungal phytase-added diets at 0, 250, 500, 750, 1,000, or 1,250 FTU/kg (as-fed basis; one phytase unit or FTU is defined as the quantity of enzyme required to liberate 1 micromol of inorganic P/min, at pH 5.5, from an excess of 15 microM sodium phytate at 37 approximately C) and a positive control diet, eight individually penned 10-kg pigs per diet (12 diets, 96 pigs) were used in a 28-d growth study. The third experiment was a 10-d nutrient balance study involving six 13-kg pigs per diet (four diets, 24 pigs) in individual metabolism crates. In Exp. 4, eight pens (four pigs per pen) of 19-kg pigs per treatment were used in a 42-d growth performance study to examine the effect of adding the E. coli-derived phytase to corn-soybean diets at 0, 500, or 1,000 FTU/kg (as-fed basis) and a positive control (four diets, 128 pigs). In Exp. 5, six 19-kg pigs per treatment were used in a 10-d nutrient balance study to investigate the effects of the E. coli-derived phytase added to diets at 0, 250, 500, 750, or 1,000 FTU/kg (as-fed basis) and a positive control diet (six diets, 36 pigs). The in vitro study showed that the E. coli-derived phytase has an optimal activity and pH range of 2 to 4.5. Inorganic phosphate release was greatest for soybean meal, least for corn, and intermediate for the negative control diet. Dietary supplementation with graded amounts of E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain, feed efficiency, and plasma Ca and P concentrations in 10-kg pigs in Exp. 2. Phytase also increased P digestibility and retention in the 13-kg pigs in Exp. 3. In Exp. 4, dietary supplementation with E. coli-derived phytase resulted in linear increases (P < 0.05) in weight gain and feed efficiency of 19-kg pigs. Supplementation of the diets of 19-kg pigs with the E. coli-derived phytase also improved Ca and P digestibility and retention in Exp. 5. In the current study, the new E. coli-derived phytase was efficacious in hydrolyzing phytate-P, both in vitro and in vivo, in young pigs.

6-Phytase↗

PubMed1983

Effect of added methionine and lysine on the performance of chicks fed different alfalfa protein concentrates.

Experiments were conducted to determine the limiting amino acids in chick diets containing 40% spray-dried heat coagulated alfalfa protein concentrate (APC) and 40% spray-dried fermented alfalfa protein concentrate (FAPC). Significant improvements in chick gains were observed when methionine (met) was supplemented to the 40% APC (82 vs. 119 g) and 40% FAPC (72 vs. 95 g) diets. Feed efficiency (gain/feed) was also improved by met supplementation (.233 vs. .343) to APC and (.236 vs. .299) in FAPC diets. Supplementation of lysine (lys) alone did not improve the gain in body weight in either APC or FAPC, but the addition of lysine improved the feed efficiency of chicks fed the FAPC + Met (.323).

Animals↗

PubMed1991

The effect of acarbose on the food intake, weight gain, and adiposity of LA/N-cp rats.

1. Groups of lean and obese LA/N-cp rats were administered the intestinal glucosidase inhibitor acarbose at 150 or 300 mg/kg diet from 7 until 17 weeks of age and the effects of the drug on food intake patterns and adiposity determined. 2. Dose related effects on body weights, adiposity and feed efficiency ratio were observed (control greater than 150 mg greater than 300 mg drug/kg diet) following treatment in both phenotypes, with the greatest differences observed in the obese phenotype. 3. Acarbose at both dosages was associated with phenotype-specific alterations in food intake amount and feeding pattern, resulting in an attenuation of age-associated increases in food intake. The feed efficiency ratio decreased in both phenotypes, and approached normally fed lean controls in obese rats administered the greater dosage. 4. These results indicate that patterns of food intake and weight gain differ markedly between lean and obese rats of this strain, and acarbose brings about a dose-related attenuation of developing food intake patterns in both phenotypes and which are associated with decreases in weight gain and adiposity. Thus, this drug may have therapeutic potential as an adjunct agent in the treatment of obesity and/or other disorders of carbohydrate intolerance.

Acarbose↗

PubMed1992

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.

Animal Feed↗

PubMed2003

Effect of source of energy and rate of growth on performance, carcass characteristics, ruminal fermentation, and serum glucose and insulin of early-weaned steers.

Seventy-three crossbred steers (initial BW = 170.5 +/- 5.5 kg) from The Ohio State University (Exp. 1) and 216 crossbred steers (initial BW 135.4 +/- 4.4 kg) from the University of Illinois (Exp. 2) were used to determine the effect of source of energy and rate of growth on performance, carcass characteristics, and glucose and insulin profiles on early-weaned steers. Effects of the diets used in Exp. 1 and 2 on ruminal pH and VFA concentrations were quantified using ruminally fistulated steers (Exp. 3). Cattle were weaned at an average age of 119 d in all experiments and were allotted by age, BW, and breed to one of four diets: high-concentrate, fed ad libitum (ALCONC), high-concentrate fed to achieve a gain of either 1.2 kg/d (1.2CONC) or 0.8 kg/d (0.8CONC), or high-fiber, fed ad libitum (ALFIBER). At 218 d of age, all steers were placed on the ALCONC diet until slaughter. Steers were implanted with Compudose at the initiation of all experiments and with Revalor-S when they were estimated to be 100 d from slaughter. When steers in Exp. 1 averaged 181 and 279 d of age, serum samples were collected to determine glucose and insulin concentrations. Steers were slaughtered when a fat thickness of 1.27 cm was reached (Exp. 1) or after 273 d on feed (Exp. 2). In Exp. 1, days in the feedlot (P < 0.01) and age at slaughter (P < 0.01) were lowest for ALCONC and ALFIBER steers, and greatest for 0.8CONC steers. Overall, ADG was greatest for ALCONC and lowest for 0.8CONC steers; feed efficiency was lowest (P < 0.01) for ALFIBER steers. Final BW did not differ (P > 0.57) among treatments. At 181 and 218 d of age, serum insulin was increased (P < 0.10) and intramuscular fat percentage was greatest (P < 0.07), respectively, for ALCONC steers. In Exp. 2, overall ADG (P < 0.06) and final BW (P < 0.04) were greatest for ALCONC and lowest for 1.2CONC and 0.8CONC steers. Overall feed efficiency was greatest for 0.8CONC and lowest for ALFIBER (P < 0.01). Growing phase diet did not affect marbling score at 218 d of age or at slaughter (P > 0.81). In Exp. 3, differences in ruminal pH after feeding may have been a consequence of increasing acetate (ALFIBER), propionate (ALCONC), or a combination of VFA (0.8CONC and 1.2CONC), respectively (diet x time after feeding, P < 0.10). Controlling growth by limit-feeding a high-concentrate diet for only 100 d does not extend the growth curve of early-weaned steers or enhance intramuscular fat deposition at slaughter compared to ad libitum intake of a high-concentrate or high-fiber diet.

Adipose Tissue↗

PubMed1991

Lysine requirements of fast- and slow-growing broiler chicks.

Experiments were conducted to determine the lysine requirement of fast-growing (Hubbard x Hubbard) and slow-growing (New Hampshire x Columbian) broiler chicks during the period 8 to 21 days posthatching. A lysine-deficient diet (.51% digestible lysine; 23% CP; 3,200 kcal MEn/kg) based upon corn, feather meal, and soybean meal was supplemented with 10 graded increments of L-lysine.HCl to produce three- to fourfold responses in weight gain. Requirements for digestible lysine were determined to be not greater than 1.01% of the diet for maximal weight gain of both strains. Maximal gain:feed ratio was achieved in both strains at a digestible lysine level not greater than 1.21% of the diet. Daily feed consumption of the fast-growing strain was over twice that of the slow-growing strain, and the digestible lysine requirement for maximal feed efficiency was 675 mg/day for fast-growing chicks compared with 318 mg/day for slow-growing chicks. The portion of the weight gain comprised of protein was roughly the same in both strains. It is evident that the slow-growing crossbred broiler strain. Translating the digestible lysine requirement of 1.21% of the diet to practice, wherein a corn and soybean meal diet would be fed, results in a total lysine requirement of 1.41% of the diet (for maximal feed efficiency) during the broiler chick's 2nd and 3rd wk of life.

Animal Feed↗

PubMed1995

The effects of halofuginone and salinomycin, alone and in combination, on live performance and skin characteristics of broilers.

Live performance and skin characteristics of male and female broilers were evaluated under four coccidiostat feed additive programs. Treatments consisted of halofuginone (H) and salinomycin (S), fed either continuously (HH and SS) or in rotational programs (HS and SH) during the starter (1 to 21 d) and grower (22 to 35 d) periods, respectively. An unmedicated withdrawal feed was provided from 36 to 42 d of age. Body weights, feed efficiency, and mortality (by pen) were determined, in addition to skin puncture strength measurements taken at Days 21, 35, and 42 on five birds per pen. At 43 d of age, all birds were processed and individually graded for skin defects. There were no treatment by sex interactions for any variable measured. Male body weights, feed efficiency, and total mortality exceeded those of females (P < .05). Skin puncture strength was reduced at 21 d in the HH and HS groups, at 35 d in the HH and SH groups, and at 42 d in the HH, HS, and SH groups. Thigh sores and scratches were higher for the HH group (P < .05), and thigh skin tears were higher for the HH and HS groups (P < .01). Males had more swollen hock joints and breast blisters than females (P < .001). Females had more thigh skin tears (P < .01) and broken wings (P < .001) than males. Results of the present study demonstrated that halofuginone affected skin strength of broilers, especially when used continuously or only in the starter feed (1 to 21 d).

Animals↗

PubMed1993

Effect of a soybean hull:soy lecithin:soapstock mixture on ruminal digestion and performance of growing beef calves and lactating dairy cattle.

Four experiments were conducted to evaluate the effect of a soybean hull, soy lecithin, and soapstock mixture on ruminal fiber and protein digestion, growth efficiency of beef calves, and lactational performance of dairy cattle. An initial mixing experiment determined that a 4:1 ratio (DM basis) of soy lecithin:soapstock could be added to soybean hulls at 15% (wt/wt, DM basis); this mixture had acceptable mixing and handling characteristics. Dietary addition of a mixture of 85% soybean hulls, 12% soy lecithin, and 3% soapstock (DM basis; SLS) to provide 0, 3, 5, or 7% supplemental fat resulted in a linear (P < .01) decrease in in situ rate of ruminal NDF digestion with no effect on rate of CP digestion. Daily gain, DMI, and feed efficiency (kilograms of gain/kilogram of DMI) of growing beef calves were not affected (P > .10) as graded levels of SLS replaced corn grain. However, as graded levels of SLS replaced soybean hulls, daily gain and feed efficiency increased linearly (P < .01). Based on the results of these trials, Holstein dairy cattle were fed four isonitrogenous and isoenergetic diets that contained either high levels of nonfiber carbohydrates (43%) and no added fat, 1% ruminally inert fat, a 6% level of SLS, or a 12% SLS level (all on DM basis). Efficiency of 4% fat-corrected milk production (kilograms of milk/kilogram of DMI) was greatest for cows fed SLS at 6% of dietary DM. The SLS mixture was an excellent source of fiber and vegetable fat, comparable in feeding value to corn grain, for inclusion in the diets of beef calves and dairy cows.

Animal Feed↗

PubMed2000

The effects of active immunization against gnRH on testicular development, feedlot performance, and carcass characteristics of beef bulls.

The objective was to determine the effects of a recombinant fusion protein anti-GnRH vaccine on testicular development, feedlot performance, and carcass quality of beef bulls. Crossbred beef bulls (n = 58, average weight 306 kg, 9 mo of age), were randomly allocated to two groups and received either an anti-GnRH vaccine (GnRH) or placebo (Control) by intramuscular injection on d 0, 56, and 112. There were group effects (P < 0.01; as a percentage of Control) on testicular weight (53%), daily sperm production (40%), and epididymal sperm reserves (16%). There were group x time interactions (P < 0.0001) for scrotal circumference and serum testosterone concentrations; at slaughter, bulls in the GnRH group had a smaller (P < 0.05) scrotal circumference (28.3 vs 33.9 cm) and lower (P < 0.05) serum testosterone concentrations (2.2 vs 8.6 ng/mL) than those in the Control group. Average daily gain, feed intake, and feed efficiency were not different between treatments during the backgrounding phase (d 0 to 84). During the finishing phase (d 98 to 182), ADG was greater (P < 0.05) for bulls in the Control group (1.69 vs 1.42 kg/d), as was carcass weight (6.9%; P < 0.01). However, GnRH bulls had numerically better feed efficiency (6.12 vs 7.08 kg DMI/kg gain; P < 0.23) and shear force values for ribeye that were 16% lower (P < 0.14) than Control bulls, warranting further investigation. Vaccinating bulls against GnRH suppressed testicular function, with growth and carcass characteristics similar to that expected with steers.

Animal Husbandry↗

PubMed1999

Adrenalectomy reduces adiposity by decreasing food efficiency, not direct effects on white adipose tissue.

OBJECTIVE: This study was conducted to establish the effects of adrenalectomy (ADX) on adipose tissue metabolism in male Sprague-Dawley rats fed a standard chow diet. RESEARCH METHODS AND PROCEDURES: The effects of adrenalectomy on adipose cell size, lipoprotein lipase activity, and basal and insulin-stimulated glucose conversion to lipid and lipolysis were measured. RESULTS: ADX decreased body weight gain during the post-operative period in the absence of changes in food intake; feed efficiency was decreased significantly. ADX decreased adipocyte size by 30%. ADX increased adipocyte response to the effect of submaximal concentrations of insulin on lipid synthesis and lipolysis. ADX decreased maximally insulin-stimulated lipid synthesis, but this effect was accounted for by decreased adipocyte size. In contrast, ADX had no effect on maximally insulin-inhibited lipolysis. ADX did not affect heparin-releasable LPL. The small effect of ADX on residual extractable adipose tissue LPL activity was accounted for by decreased fat cell size. DISCUSSION: ADX decreased adiposity in the absence of changes in food intake, lipoprotein lipase activity, and adipocyte lipid metabolism. The effect is best attributed to decreased feed efficiency.

Adipocytes↗

PubMed2002

Manipulation of growth in pigs through treatment of the neonate with clenbuterol and somatotropin.

Neonatal pigs were treated with lipolytic agents to determine whether this would cause a long-term decrease in their ability to deposit fat, with a consequent increase in muscle growth and feed efficiency. Groups of 25 female piglets were given clenbuterol (100 microg/kg BW), porcine somatotropin (pST; 100 microg/kg BW), pST plus clenbuterol, or saline injections from 3 d to 40 d of age. Five piglets from each group were then slaughtered to determine body composition. Clenbuterol and pST both increased ADG up to weaning when given separately (24%, P < 0.05; 20%, P < 0.1 respectively) but did not reduce fat deposition. In contrast, pigs given clenbuterol plus pST showed no increase in ADG and a 41% reduction in carcass fat (P < 0.05). Clenbuterol caused a marked decrease in beta2-adrenoceptor density in porcine adipose tissue (P < 0.001) and skeletal muscle (P < 0.01). This effect was attenuated by concurrent pST treatment, which helps to explain the synergistic effect of these drugs on fat deposition. Once the drugs were withdrawn at 40 d, the anabolic effect of pST gradually disappeared, so that the live weight of pST-treated and control pigs was identical at 168 d. Clenbuterol withdrawal caused the rapid loss of extra weight gained, plus an additional 4 to 5 kg live weight that was never recovered. During the 4-wk finishing period there was an increase in feed intake in pigs that had previously undergone treatment with pST (23%, P < 0.1), with no increase in ADG, and so feed efficiency was impaired (P < 0.05). Pigs that were treated with pST plus clenbuterol showed no marked increase in feed intake during this period. Carcasses from clenbuterol-treated pigs tended to be leaner at 168 d, but there was no long-term effect of pST or the combined treatment on carcass composition. Overall, the treatment of neonatal pigs with repartitioning agents was counter-productive, due to the withdrawal effects of the beta-adrenefgic agonist and the delayed long-term effect of pST on feed intake.

Adipose Tissue↗

PubMed1997

Effects of diet supplementation and body cooling on Friesian calves reared in high ambient temperatures in the eastern desert of Egypt.

Four groups of 10 Friesian male calves were fed on rice straw ad libitum and concentrate for 2 months. The first group was fed in winter. The other 3 groups (1, 2 and 3) were fed in summer. Group 1 was fed the same diet as the winter group, Group 2 was fed on the same diet as Group 1 but it was supplemented with urea and a minerals and vitamins mixture and Group 3 animals were fed on the same diet as Group 1 and cooled by sprinkling and drinking cool water. The results showed that high ambient summer temperatures induced highly significant decreases in weight gain and feed efficiency and deleterious effects on thyroid, liver and kidney functions. The diet supplemented with urea, minerals and vitamins improved liveweight gain and restored some blood components, but the effects of high ambient temperature were not completely alleviated since the calves still had increases in transaminase enzyme activities, rectal temperature and respiration rate. Cooling the animals during summer led to improved body liveweight gain, feed efficiency and certain body functions. In addition, the cooling treatment reduced the heat load and aided the animals to reach a steady physiological state, confirming that the cooling treatment was more effective than diet supplementation in removing heat load during the summer.

Animal Feed↗

PubMed1976

Liver lipid accumulation and performance of hens as affected by cage density and initial body weight.

Hens housed in individual cages (25 46 cm.) laid significantly more eggs, consumed significantly more feed and had significantly larger livers with a higher lipid content than hens housed three to a cage in two experiments. Body weight gain was significantly higher for individually housed birds in experiment 1, but not in experiment 2. No difference was observed in mean egg weight or kg. feed per dozen eggs. In experiment 2 hens housed two to a cage laid slightly fewer eggs and accumulated slightly less liver fat but the differences were not significantly different fromthose housed individually. Hens socially dominant in three bird pens had higher liver fat accumulation than hens lower on the peck order but liver fat accumulation for the dominant hens still averaged less than hens housed either two or one per cage. Comparison of two strains in experiment 1 revealed a significant difference in rate of egg production and feed efficiency but no difference in liver fat accumulation. Pullets placed in four body weight classes prior to the start of the experiment did not differ significantly in liver fat accumulation per unit of body weight or percentof dry matter of the liver at the end of the experiment. Rate of egg production and feed efficiency were also not significantly different among the body weight classes.

Animals↗

PubMed1997

Final-week performance of straight-run broilers as affected by early coccidiostat withdrawal followed by increased dietary salt.

Three experiments were conducted to evaluate elevated dietary NaCl levels as a means of offsetting industry-observed reductions of growth, feed intake, and feed efficiency associated with early (35-d) coccidiostat withdrawal. In the first experiment, monensin (100 ppm) was withdrawn and dietary salt levels of 0.33, 0.48, 0.63, 0.78, or 0.93% provided from 35 to 42 d of age. Experiments 2 and 3 involved lasalocid (110 ppm) withdrawal and slat amounts of 0.33, 0.53, 0.73, or 0.93%. In all studies, a positive control of 0.33% salt and the coccidiostat was also given. Monensin withdrawal reduced body weight gain, which was not overcome by slat addition. Feed efficiency during the 1-wk period was improved to the level of the group receiving continued medication by salt amounts of 0.78% or above. In contrast to industry field observations, removal of lasalocid did not reduce body weight gain, feed intake, or water consumption, and elevation of salt levels resulted in no consistent improvements of weight gain, feed intake, or feed conversion. Water intake increased proportionally as salt concentration increased. Elevated salt levels do not appear to be a reliable means of offsetting reduced performance related to early coccidiostat withdrawal, nor were such performance problems demonstrable for lasalocid in these trials.

Aging↗

PubMed1981

Arginine requirement and apparent absence of a lysine-arginine antagonist in fingerling channel catfish.

A series of growth studies, utilizing casein-gelatin based diets supplemented with crystalline amino acids, were conducted to determine the arginine requirement for fingerling channel catfish (Ictalurus punctatus) and to evaluate the effects of excessive levels of dietary lysine and arginine. Weight gain and feed efficiency data indicate the arginine requirement to be 1.03 +/- 0.07% and 1.00 +/- 0.06% of the dry diet, respectively. Based on growth this corresponds to 4.29% of the dietary protein. There was no evidence of an arginine-lysine antagonism when excess lysine was fed in diets adequate or marginal in arginine. Similarly, growth and feed efficiency data suggest the lack of an antagonism when excess arginine is added to diets marginal in lysine. Apparently channel catfish are not as sensitive to disproportionate lysine and arginine levels as are other animals.

Animals↗

PubMed1989

Effect of iodine-treated water on the performance of broiler chickens reared under various stocking densities.

A total of 544 day-old sexed broiler chicks were used to investigate the effects of 2 ppm iodine-treated water on body weight and feed efficiency when the chicks were reared at 900, 720, 540, and 360-cm2 stocking densities. Chicks were fed a corn-soybean meal diet calculated to contain 3,212 kcal ME/kg and 21.58% CP. Iodine added to the drinking water at the rate of 2 ppm improved growth significantly after 4 wk of age. Feed efficiency was not significantly affected by the addition of iodine to the drinking water. Maximum effects on growth were obtained when the broilers were housed at stocking densities of 720 and 540 cm2/bird. A stocking density of 360 cm2 appeared to provide a crowding stress severe enough to negate the beneficial effects of adding iodine to the drinking water.

Animals↗