Alternatives to replace antibiotics in broiler diets : effects on protein utilization and production performance

[摘要] ENGLISH ABSTRACT: Different substances were evaluated and compared to an antibiotic, in terms of their effect on nitrogen- and amino acid digestibilities. Two digestibility trials and one performance trial were conducted.Trials one and two apparent nitrogen (AND)- and amino acid (AAD) digestibilities were determinedfrom digesta collected at the terminal ileum (ileal digestibility method). In Trial 3 the substances wereevaluated in terms of their potential to improve production performance. Broilers were fed a maizesoyabased diet throughout the three trails.In the first trial, garlic and a commercial prebiotic (Bio-Mos®), were tested and compared in terms ofAND and AAD, to an antibiotic (doxycyclin, Doxyvete-SOS). A starter and finisher diet were fed aseither mash or pellets. The garlic was included at 8g/kg, 13g/kg and 18g/kg to the starter and finisherdiets. Bio-Mos® was added at 1g/kg, 2g/kg and 3g/kg to the starter diet, and 0.5g/kg, 1g/kg and1.5g/kg to the finisher diet. The doxycyclin was added at 0.3 g/kg. None of the treatments had anybeneficial effects in terms of AND. Feeding a pellet seem to have some negative effects in terms ofAND. In general most of the treatments did not show any improvement in AAD at any determinationperiod (day 21, 28 or 35). At day 21 and day 35, the mash diet supplemented with 18g/kg garlic had anegative effect on AAD, when compared to the negative and positive control. It doesn't seem thatfeeding either a mash or a pellet had an influence on the effects exerted by the different treatments.In the second trial the influence of Bio-Mos®, a blend of organic acids, probiotics and electrolytes(Acid-Pak 4-way®) and a medium-chain triglyceride (MCT) were evaluated and compared in terms ofAAD and AND, to the effect of an antibiotic, doxycyclin. The starter and finisher diets were fed as amash. Bio-Mos® was included at 1g/kg, 2g/kg, and 3g/kg in the starter diet, and at 0.5g/kg, 1g/kg,1.5g/kg in the finisher diet, respectively. Acid-Pak 4-way® was included at 0.4g/kg, 1g/kg and 1.6g/kgfor both the starter and finisher diets. Medium-chain triglycerides (MCT) were allocated at 3g/kg,3.6g/kg, 4.2g/kg for the starter diet, and 2.1g/kg, 2.7g/kg and 3.4g/kg for the finisher diet. An antibiotic,doxycyclin, was included at 0.3 g/kg. With AND, no treatment had any significant effect for the entireexperimental period. At day 21, the treatment supplemented with MCT (3.4g/kg) had the mostsignificant beneficial effect on AAD, when compared to the negative- and positive controls, as itincreased AAD for the majority of the amino acids. The treatment with Acid-Pak 4-way® (1g/kg) hadthe most significant negative effect on AAD when compared to the positive control. At day 28, thetreatments with Bio-Mos® (0.5g/kg and 1.5g/kg) and Acid-Pak 4-way® (0.4g/kg) had the mostsignificant beneficial effect on AAD when compared to the positive control. It increased AAD for morethan half of the 17 amino acids evaluated. The treatment supplemented with MCT (2.7g/kg) hasshown the most significant negative effect on AAD, when compared to the positive control.In the third trial the effect of Bio-Mos®, Acid-Pak 4-way® and MCT on production performance wasevaluated, and compared to the effects of the presence or absence of doxycyclin. Body weight (BW),body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) were measured. The starter and finisher diets were fed as a mash. Bio-Mos®, MCT and Acid-Pak 4-way® were included at3.0g/kg, 4.2g/kg and 1.6g/kg, respectively in the starter and finisher diets. Birds were weighed (perpen) on arrival and on days 7, 14, 21, 28, 35. Feed intake (FI) per pen was measured at days 7, 14,21, 28 and 35, and mortality was recorded daily. In terms of BWG, Acid-Pak 4-way® had a higherBWG, when compared to the negative control, Bio-Mos® and MCT.It can be concluded that Bio-Mos®, Acid-Pak 4-way®, as well as MCT can be a possible alternativesto antibiotic supplementation. These three treatments did not necessary prove to be more effectivethan antibiotics, but are definitely competitive alternatives.

[发布机构] Stellenbosch University