Organic acid blend in diets of broiler chickens challenged with Clostridium perfringens

This study was conducted to evaluate the effects of a blend of organic acids (OAs) in diets with or without antibiotic growth promoter (AGP) in chickens challenged with Clostridium perfringens. Day-old male broiler chicks were used in a trial with 4 treatments and 6 replicates of 50 birds per pen, for 43 days, in a completely randomized design. The treatments in a 2×2 factorial arrangement consisted of the presence or absence of enramycin (AGP) and of a blend of OA in the feed. All birds were inoculated at 7 days of age with an anticoccidial vaccine in the drinking water; on days 14, 15, and 16, they were inoculated with C. perfringens in the feed. OA improved weight gain, body weight, and feed intake in the periods 1–7 days and 1–21 days in chicks without antibiotic supplementation. The AGP had the main effect of increasing weight gain and body weight at 35 d; the OA increased weight gain, body weight, and feed intake at 43 days of age. The birds supplemented with OA without AGP had a higher number of CD3+ cells in the ileum mucosa and lower crypt depth than birds supplemented with both OA and antibiotic at 7 days. At 21 days of age, birds fed OA without AGP had higher villus height and a larger villus/crypt ratio; however, there were no differences in the CD3+ cells in the ileal mucosa. The use of OA was beneficial for weight gain and AGP for feed conversion, and the combination of OA and AGP brings complementary advantages in production.     

Fatty acid and energy metabolism in broiler chickens fed diets containing either beef tallow or an oil blend

The hypothesis tested was that the feeding of n‐6 polyunsaturated fatty acids (PUFA) results in more whole‐body fatty acid oxidation than the feeding of saturated fatty acids (SFA). It was reasoned that the increased fatty acid oxidation would be associated with enhanced whole‐body energy expenditure and stimulated de novo fatty acid synthesis. To put the hypothesis to the test, broiler chickens were fed diets containing either beef tallow as source of SFA or an oil blend as source of n‐6 PUFA. The broilers either had free access to their diet or were fed a restricted amount. Seven‐day‐old, male broiler chickens were used; they were kept individually in cages from 1 to 4 weeks of age. In the birds fed ad libitum, the n‐6 PUFA diet reduced average daily feed intake (ADFI), but did not significantly affect average daily weight gain (ADG) and the feed:conversion ratio (FCR). The lower ADFI on the n‐6 PUFA diet was associated with a higher apparent digestibility of total fatty acids. The ratio of deposition in the body to intake of digestible total PUFA, which reflected n‐6 PUFA, was significantly decreased by the n‐6 PUFA diet, pointing at preferentially increased n‐6 PUFA oxidation on the n‐6 PUFA diet. The ratio for n‐9 monounsaturated fatty acids (MUFA) was higher than 1.0, which agrees with net de novo synthesis, but the n‐6 PUFA diet induced a lower value than did the SFA diet. Feeding either the n‐6 PUFA or SFA diet did not influence energy expenditure expressed as percentage of energy intake. This study supports the idea that dietary n‐6 PUFA instead of SFA are preferentially oxidized, but no proof was obtained for enhanced energy expenditure and contrary to the hypothesis put forward, the n‐6 PUFA diet depressed de‐novo fatty acid synthesis.     

Performance and meat quality of broiler chickens that are fed diets supplemented with Agaricus brasiliensis mushrooms

This trial was performed to study the use of the mushroom Agaricus brasiliensis as an alternative additive to antimicrobial growth promoters in broiler chicken diets and to assess the quality of the broiler chicken breast meat of birds that are fed diets containing this fungus. Thus, 595 1-day-old chicks were reared in reused poultry litter without anticoccidial and antimicrobial additives. The results showed that a concentration of 1.6 g mushrooms/kg diet was ideal for these birds because it provided better bird performance. When the birds’ immune system organs were analyzed, it was found that the addition of both mushrooms influenced the immune system organs of these broiler chickens. Adding A. brasiliensis to broiler chicken diets did not compromise breast meat quality.     

Grass meal as an ingredient in diets for broiler chickens

1. Six diets of equal energy and nitrogen contents containing between 0 (control) and 125 g grass meal/kg were each fed to 4 groups of 42 male and 4 groups of 42 female broiler chicks, in floor pens, from 0 to 56 d of age.

2. Increments of 25 g grass meal/kg and 7.3 g maize oil/kg replaced a mixture of soyabean, wheat and barley meals in the control diet.

3. Gain: food ratio (y) of the birds decreased linearly as dietary grass meal content (x) increased such that y = 0.4295 ? 0.0032x.

4. Carcass analyses indicated that the decrease in gain : food ratio was caused by less deposition of body fat.

5. Skin colour became significantly yellower as the dietary grass meal content increased.     

Energy and protein utilisation by broiler chickens fed diets containing cottonseed meal and supplemented with a composite enzyme product

ABSTRACT

1. The present study examined the potential of new-generation microbial enzymes to improve the utilisation of energy and protein of cottonseed meal (CSM)-containing diets, with the aim of increasing its inclusion level in broiler chickens diets.

2. Four hundred and eighty, one-day-old Ross 308 male broilers were used to assess the utilisation of energy and protein by broiler chickens fed diets containing four graded levels of CSM – none, low (4, 8, 12%), medium (5, 10, 15%) or high (6, 12, 18%) in the starter, grower, and finisher phases, respectively, supplemented with 100 mg/kg of a composite enzyme product (xylanase and β-glucanase).

3. Inclusion of CSM improved (P < 0.01) apparent metabolisable energy (AME), with further improvement (P < 0.001) seen in the enzyme-supplemented diets. Inclusion of CSM reduced (P = 0.002) the metabolisable energy intake (MEI), but this was increased (P < 0.05) with enzyme supplementation.

4. Enzyme addition increased (P < 0.001) the net energy of production (NEp), while heat production (HP) decreased (P < 0.001) with CSM inclusion. More energy was retained as fat (P < 0.05) and protein in birds fed diets with the enzyme, but this was reduced (P < 0.029) by CSM.

5. There was an increase (P < 0.05) in efficiencies of ME use for energy, lipid and protein retention, with higher CSM levels. The enzyme improved (P < 0.013) efficiency of ME use for lipid retention.

6. Feeding diets containing CSM to the broilers enhanced (P < 0.05) protein intake (PI) and protein efficiency ratio (PER). Positive effects (P < 0.05) of enzyme were observed on protein gain (PG) and net protein utilisation (NPU).

7. Results obtained from this study suggested that nutrient utilisation of diets containing CSM by broiler chickens can be improved by enzyme supplementation.     

Efficacy and equivalency of an Escherichia coli-derived phytase for replacing inorganic phosphorus in the diets of broiler chickens and young pigs

Two studies were conducted to determine the efficacy of an Escherichia coli-derived phytase (ECP) and its equivalency relative to inorganic phosphorus (iP) from monosodium phosphate (MSP). In Exp. 1, one thousand two hundred 1-d-old male broilers were used in a 42-d trial to assess the effect of ECP and iP supplementation on growth performance and nutrient digestibility. Dietary treatments were based on corn-soybean meal basal diets (BD) containing 239 and 221 g of CP, 8.2 and 6.6 g of Ca, and 2.4 and 1.5 g of nonphytate P (nPP) per kg for the starter and grower phases, respectively. Treatments consisted of the BD; the BD + 0.6, 1.2, or 1.8 g of iP from MSP per kg; and the BD + 250, 500, 750, or 1,000 phytase units (FTU) of ECP per kg. Increasing levels of MSP improved gain, gain:feed, and tibia ash (linear, P < 0.01). Increasing levels of ECP improved gain, gain:feed, tibia ash (linear, P < 0.01), apparent ileal digestibility of P, N, Arg, His, Phe, and Trp at d 21 (linear, P < 0.05), and apparent retention of P at d 21 (linear, P < 0.05). Increasing levels of ECP decreased apparent retention of energy (linear, P < 0.01). Five hundred FTU of ECP per kg was determined to be equivalent to the addition of 0.72, 0.78, and 1.19 g of iP from MSP per kg in broiler diets based on gain, feed intake, and bone ash, respectively. In Exp. 2, forty-eight 10-kg pigs were used in a 28-d trial to assess the effect of ECP and iP supplementation on growth performance and nutrient digestibility. Dietary treatments consisted of a positive control containing 6.1 and 3.5 g of Ca and nPP, respectively, per kg; a negative control (NC) containing 4.8 and 1.7 g of Ca and nPP, respectively, per kg; the NC diet plus 0.4, 0.8, or 1.2 g of iP from MSP per kg; and the NC diet plus 500, 750, or 1,000 FTU of ECP per kg. Daily gain improved (linear, P < 0.05) with ECP addition, as did apparent digestibility of Ca and P (linear, P < 0.01). Five hundred FTU of ECP per kg was determined to be equivalent to the addition of 0.49 and 1.00 g of iP from MSP per kg in starter pigs diets, based on ADG and bone ash, respectively.     

Performance and physiological responses of broiler chickens to supplemental guanidinoacetic acid in arginine-deficient diets

1. The present experiment was designed to examine arginine (Arg)-sparing effects of guanidinoacetic acid (GAA) on production performance, intestinal morphology and certain blood parameters in broiler chickens.

2. A total of 300 male broiler chicks (Ross 308) were randomly allotted to 5 dietary treatments in a completely randomised design during 1–15 and 15–35 d rearing periods. Experimental treatments consisted of a basal diet with a reduction in Arg content (CON?; starter: 12.1 g/kg and grower: 11.3 g/kg Arg), a CON? diet supplemented with synthetic Arg equal to the required Arg level (CON+; starter: 13.80 g/kg; grower: 12.37 g/kg) and CON? diet supplemented with three levels of GAA (GAA0.6; GAA1.2; and GAA1.8; g/kg).

3. Supplemental GAA at 0.6 and 1.2 g/kg reduced the adverse effects of the CON? diet on weight gain and feed conversion ratio in the starter period, equal to the effect of CON+ diet. During the entire rearing period, such an effect was only seen for broilers fed CON? diet supplemented with 1.2 and 1.8 g/kg GAA (P < 0.05). Proportional weights of liver and abdominal fat were decreased in birds fed diets containing supplemental Arg and 1.8 g/kg GAA compared to the CON? broilers (P < 0.05). Jejunal villus height and villus height to crypt depth ratio were increased in broilers receiving the CON? diet (P < 0.05). Serum concentration of nitric oxide increased when the CON? diet was supplemented with either Arg or 1.8 g/kg GAA (P < 0.05).

4. Dietary inclusion of GAA had an Arg-sparing effect, whereby 1.2 and 1.8 g/kg of supplemental GAA resulted in greater growth performance during the starter and entire rearing periods, respectively. Supplementation with 1.8 g/kg GAA had significant effects on some carcass and physiological parameters.     

Effect of clenbuterol on growth,carcase and skeletal muscle characteristics in broiler chickens

1. Male and female broiler chickens (144 in total) were given diets supplemented with clenbuterol (CB) at 0 (control) and at 1 mg/kg between 28 and 49 d of age to study the effect of CB on growth, carcase and skeletal muscle.

2. CB improved growth in males by increasing daily weight gain and final live weight and by lowering food conversion ratio. In females it changed the carcase composition by reducing abdominal fat pad and by increasing the proportion of protein. Consequently, carcase protein gain was increased in both sexes (11% and 16%, respectively).

3. Skeletal muscle weights were enhanced by between 6% and 22%. Muscle fibre diameters were increased in extensor hallucis longus (EHL) but not in gastrocnemius (GAS) muscle. This increase was more pronounced in females. EHL total muscle fibre number remained unchanged. The proportion of fast‐twitch glycolytic fibres was increased at the expense of fast‐twitch oxidative fibres in males only. Nuclear/cytoplasm and DNA/protein ratios tended to be decreased by CB.

4. From the elevated EHL muscle RNA/DNA, unchanged protein/RNA and translation activity it is suggested that CB stimulated protein synthesis at the pretranslational level. Reduced protein degradation is deduced from decreased neutral calcium‐dependent proteolytic activity.

5. It is concluded that broiler chickens respond to long‐term CB treatment as has been shown in various mammals. However, the sex‐specific response in growth, carcase composition and skeletal muscle cellularity is more clearly apparent in broiler chickens.     

Performance and bone development in broiler chickens given 25-hydroxycholecalciferol

1. A series of 5 trials was conducted with Cobb chickens in order to determine the effect of 25-hydroxycholecalciferol (25OHD3) on their performance and bone development under adequate Calcium (Ca) and Phosphorus (P) supplementation, and under moderate dietary restriction of Ca and P. Formulated beadlets of 25OHD3, trade name HY-D (IsoGen, Naperville, IL, USA) were used as the 25OHD3 source. 2. Five to 10 microg of cholecalciferol (vitamin D3) or 25OHD3/kg diet were sufficient to ensure normal body weight (BW) and bone ash in chickens under continuous lighting. The two materials had similar effects on BW and bone ash. 3. In one out of the three experiments, 25OHD3 increased BW and BW gain, while in the others it had a similar effect to that of vitamin D3, or even a slight negative effect in a trial conducted on the floor, in which the diets were supplemented with the D sources at 75 microg/kg. The effects of both D sources on bone ash and on the severity or frequency of tibial dischondroplasia were similar. 4. 25OHD3 restrained the effect of moderate dietary P restriction, but not of Ca restriction, on BW gain and bone ash in 22-d-old chickens. This effect could not be explained by an higher P bioavailability in the 25OHD3-fed chickens.     

A blend of benzoic acid and essential oil compounds as an alternative to antibiotic growth promoters in broiler diets

The discussions about the possibility of bacterial resistance resulting from the use of antimicrobial growth promoters in broiler feed. The limitations of international market have forced the exporting countries to search for alternatives to ensure the animal growth without affecting the quality of the final product. An experiment was conducted to evaluate the efficacy of in-feed CRINA® Poultry Plus (CPP, a mixture of benzoic acid and essential oils) in enhancing broiler growth performance and reducing coccidial lesions, as a non-antibiotic growth promoter. Effect of CPP on litter moisture content was also assessed. The treatments were: NC, a basal diet without growth promoters; PC, a basal diet with 10 ppm of Avilamycin (AVI); CPPD, a basal diet with 300 ppm of CPP from 1 to 42 d; AVI_(1–21d)/CPP_(22–42d), a basal diet with 10 ppm of AVI from 1 to 21 d and 300 ppm of CPP from 22 to 42 d; and AVI + CPP (1–42 d), a basal diet with 10 ppm of AVI and 300 ppm of CPP from 1 to 42 d. The 5 treatments were applied in a completely randomized arrangement and 10 replicate with 31 birds per pen. The diets with CPP increased body weight gain and feed conversion rates in the 1 to 42 d period and European productive efficiency index compared to birds fed with negative control diet (NC). Furthermore, lesion scores induced by E. acervulina were highest in the NC. The results suggest that CRINA® Poultry Plus can be used as an alternative to antibiotic growth promoters in broiler diets without losses in productive performance.     

Haematological parameters,serum lipid profile,liver function and fatty acid profile of broiler chickens fed on diets supplemented with pomegranate seed oil and linseed oil

1. The objective of the present study was to determine effect of pomegranate seed oil (PSO) and linseed oil (LO) on haematological parameters, serum lipid profile and liver enzymes as well as fatty acids profile of adipose tissue in broilers.

2. Broilers (n = 400) were fed on diets containing graded PSO levels (0.0%, 0.5%, 1.0%, 1.5%) with or without 2% LO. After 6 weeks of feeding, 6 male broilers from each group were slaughtered and abdominal fat, liver and blood samples were collected.

3. Mixtures of pomegranate seed oil (0.5%, 1%) with linseed oil increased white blood cell level in broilers. Total cholesterol was elevated after LO supplementation whereas administration of PSO (1.5%) significantly decreased this parameter. PSO administration caused c9,t11 conjugated linoleic acid (CLA) concentration-dependent deposition in adipose tissue. By LO addition α-linolenic acid (ALA) content was enhanced, decreasing the n-6/n-3 ratio. PSO and ALA also affected oleic acid proportion in adipose tissue. Neither pomegranate seed oil nor linseed oil had any effect on liver parameters.

4. Pomegranate seed oil had no negative effects on broiler health status and can be considered as a functional poultry meat component.

     

Effect of a novel microbial phytase on production performance and tibia mineral concentration in broiler chickens given low-calcium diets

1. In a 42-d feeding trial, 264 one-d-old, as hatched, Cobb 400 broiler chickens (6 pens per group, n = 11 per pen in a 2?×?2 factorial arrangement) were fed on two concentrations of dietary calcium (Ca) (9.0 and 7.5 g/kg in starter, 7.5 and 6 g/kg in grower phases) and supplemental phytase (0 and 500 U/kg diet).

2. During d 0–21, the high Ca + phytase diet improved body weight. During d 0–42, feed intake was increased by the low Ca diet and decreased by phytase supplementation. Feed conversion ratio during d 0–21 was improved by the high Ca + phytase diet.

3. At d 42, Ca in duodenal digesta was reduced by low dietary Ca and supplemental phytase. High dietary Ca reduced P in duodenal and jejunal digesta. Phytase reduced digesta P and increased serum P concentration.

4. Relative tibia length decreased with low dietary Ca and increased with phytase. The robusticity index of tibia was improved by the low Ca diet and phytase supplementation. Phytase supplementation increased tibia ash and concentrations of Ca, magnesium (Mg), manganese (Mn), copper (Cu), zinc (Zn) and iron (Fe) in tibia. The low Ca diet increased Mg, Mn and Fe and reduced Cu and Zn in tibia.

5. It was concluded that 7.5 g Ca/kg during weeks 0–3 and 6 g Ca/kg during weeks 3–6 sustained broiler performance and bone ash, while phytase supplementation facilitated tibia mineralisation, particularly during the grower phase.     

有机铬对热应激蛋鸡生产性能和血液生化指标的影响

试验选用91周龄新罗曼商品蛋鸡480只,按2×2双因子试验设计随机分为5组,对照组饲喂不添加铬的玉米-豆粕型基础日粮,4个试验组饲喂在基础日粮中分别添加了以吡啶羧酸铬或酵母铬来源的0.2mg/kg或0.4mg/kg的日粮,试验30d,以研究有机铬对热应激蛋鸡生产性能和血液生化指标的影响。试验结果显示:①有机铬能在一定程度上促进热应激蛋鸡的蛋白质利用,提高热应激蛋鸡的生产性能;②铬水平对血清尿素氮有极显著的影响(P<0.01),添加0.4mg/kg铬组均极显著地低于对照组(P<0.01),说明了补铬能够抑制由高温引起的蛋白质分解过程,从而起到缓解高温应激的作用;③吡啶羧酸铬和酵母铬在作用效果上无显著的差异;从经济效益方面考虑,0.4mg/kg铬水平的酵母铬和吡啶羧酸铬经济效益较高。     

The effect of supplementary dietary L-carnitine on the growth performance, serum components, carcase traits and enzyme activities in relation to fatty acid beta-oxidation of broiler chickens

1. This study investigated the effects of supplementary dietary L-carnitine on the performance, serum components, carcase traits and specific activities of hepatic enzymes related to beta-oxidation of fatty acids in broiler chickens. One hundred and eighty 1-d-old broilers were divided into 2 groups, each with 3 replicates, and given diets supplemented with 0 and 160 mg L-carnitine/kg for 6 weeks. 2. Experimental results indicated that supplementary carnitine did not significantly influence the performance and carcase characteristics of the broilers. 3. The serum triacylglycerol (TG) and nonesterified fatty acid (NEFA) concentrations in the carnitine supplemented group were significantly lower than that in the control group (P < 0.05). However, the effect on serum cholesterol, phospholipids concentrations and lipoprotein profiles were not significant (P > 0.05). 4. Carnitine palmitoyl transferase activity in the carnitine-supplemented group was significantly (P < 0.05) higher than in the control; however, carnitine supplementation did not significantly affect the activities of other fatty acid beta-oxidation enzymes. 5. The results in this study demonstrated that supplementary carnitine facilitated fatty acid transportation and did not influence the performance or carcase characteristics of broilers.     

Growth performance,carcass traits and digestive function of broiler chickens fed diets with graded levels of corn resistant starch

ABSTRACT

1. This study was conducted to assess the effects of graded levels of dietary corn resistant starch (RS) on growth performance, carcass traits, nutrient retention, digestive organ index, intestinal morphology, digestive enzyme activities, and mRNA expression of certain nutrient transporters in broiler chickens.

2. A total of 320, 1-d-old Arbor Acres broiler chickens were randomly assigned to five dietary treatments, with eight replicates of eight birds in each. These treatments included one corn-soybean control diet, a corn-soybean based diet containing 20% corn starch, and three diets supplemented with 4%, 8% and 12% RS by replacing corn starch with 6.67%, 13.33% and 20% of Hi-Maize 260® (identified as control, RS1, RS2, RS3 and RS4, respectively). The feeding period lasted 42 days.

3. Performance parameters including feed consumption, feed conversion, body weight gain and percentage of abdominal fat at d 42 of age, nutrient retention (including dry matter, fat, total starch and nitrogen free extract), and apparent metabolisable energy was measured from d 18 to 20 and d 39 to 41 and showed negative linear responses to increasing dietary RS level (P < 0.05). Birds fed the RS3 and RS4 diets showed higher relative weight of duodenum, jejunum and ileum, as well as lower villus height and villus height/crypt depth compared to the control (P < 0.05). The activity of pancreatic trypsin of birds at d 21 and 42 of age decreased linearly in response to the increase of dietary RS level (P < 0.01). There were linear changes in up-regulated mRNA expression of SGLT-1 and down-regulated mRNA expression of GLUT-2 with increasing proportion of RS at d 21 and 42 of age (P < 0.05), respectively.

4. It was concluded that feeding broilers with diets containing higher concentrations of RS impaired the development of small intestine, which resulted in lower apparent total tract retention of nutrients and poorer body weight gain, feed efficiency and carcass traits of broiler chickens.     

The effect on performance, energy metabolism and hepatic carotenoid content when phytase supplemented diets were fed to broiler chickens

Two basal diets containing an adequate and a low supply of available P (4.7 vs 2.5 g/kg diet) and three others containing a low available P but supplemented with 250, 500 and 12,500 units of phytase (FTU) per kg diet, respectively, were prepared. Each diet was fed ad libitum to birds in six metabolism cages (five birds in each cage) in a randomised block design. It was found that birds fed a high (12,500 FTU) dosage of phytase grew faster (P < 0.001) and retained proportionally more carotenoids in the liver (P < 0.05) compared to birds fed unsupplemented diet. The results suggest that dietary phytase may improve the anti-oxidative status of birds fed low P diets through enhancing dietary carotenoid availability.     

The effects of crude and refined low erucic acid rapeseed oils in diets for broiler chickens

1. The effects of feeding diets containing 15% of low erucic acid Zephyr rapeseed oil (B. napus) and of crude, refined and hydrogenated Span rapeseed oils (B. campestris) on growth and on tissue lipids of female broilers were determined.

2. Feeding refined or hydrogenated Span oil led to smaller body weights than feeding soybean oil, while refined Zephyr oil and crude Span oil supported a growth response similar to soybean oil.

3. The treatments had significant effects on the total lipid contents of heart (P ≤ 0.05) and spleen (P ≤ 0.001) but not liver.

4. There was no indication of lipid accumulation in the tissues of the chickens fed low erucic acid rapeseed oil as compared with those of the birds fed soybean oil.

5. Only small amounts of erucic acid were incorporated into heart, liver or spleen lipids when rapeseed oil was fed.     

Growth performance and meat quality of broiler chickens supplemented with Rhodopseudomonas palustris in drinking water

1. The effect of the bacterium, Rhodopseudomonas palustris, on the growth performance and meat quality of broiler chickens was investigated.

2. A total of 900-d-old Arbor Acres broilers were allocated to three experimental treatments for 6 weeks. Chicks were administered with R. palustris in drinking water as follows: (i) control group without R. palustris; (ii) treatment 1 (R1) with R. palustris of 8 × 10⁹ cells per chick per day in drinking water; (iii) treatment 2 (R2) with R. palustris of 1.6 × 10¹⁰ cells per chick per day in drinking water.

3. The results showed that, compared with that of control, both groups of R. palustris treatment increased daily weight gain and improved feed conversion ratio of broiler chickens significantly during the whole growing period of 6 weeks.

4. Both total and glutamic acid contents of chicken breast fillet in R. palustris treatment R2 were higher, while the fat content was lower, than those of the control group. Furthermore, R. palustris treatments also improved sensory attributes of chicken breast fillet.

5. As a probiotic providing rich nutrients and biological active substances, R. palustris administration in drinking water displayed a growth promoting effect and improved meat quality of broiler chickens.     

Salmonella colonization in young chickens given feed supplemented with the growth promoting antibiotic avilamycin

The feed given to young broiler chickens was contaminated artificially with Salmonella kedougou, a serotype associated with both subclinical infections in commercially reared chickens and food poisoning in humans. No evidence was obtained to suggest that the growth promoting antibiotic avilamycin, added to the feed at the rate of either 2.5 ppm or 10 ppm, had the undesirable side-effect of favouring the colonization of the intestinal tract of the birds with Salmonella kedougou when they were challenged with this organism in the feed.