ISSUE FOCUS 50 FEED & ADDITIVE MAGAZINE June 2024 FCR (T1). Betaine also showed a significant effect, independent of the temperature. In both thermal-neutral and heat-stress conditions treatments containing betaine improved broiler performance significantly. Looking at the feed conversion ratio (FCR), a significant effect on temperature x betaine was found. This means that the positive effect of betaine during heat-stress conditions is significantly higher than betaine during thermal-neutral conditions, which were already significant. No significant effect was found on the combination of extra Met + betaine. Trial results show a numerical difference in favor of diets using the Met matrix value + betaine compared to the diets supplemented with extra methionine on top of the methionine requirement. In both thermal-neutral or heat-stress conditions, the combination of the Met matrix value and betaine saw no additional improvement when more Met was used. In these instances, addition of more Met raised diet cost without improving outcomes. This result helps demonstrate the validity of the established Met matrix value in thermal-neutral and heat-stress conditions. In both thermal-neutral and heat-stress conditions, comparing the performance of birds in T1 and T2 reveals that birds that received 0.02% betaine outperformed birds receiving the treatment with Met levels at requirement and no betaine. DETERMINING THE BETTER METHYL DONOR The trial also investigated whether methionine or betaine was a better methyl donor. Researchers evaluated whether supplying extra methionine with or without betaine would further enhance growth performance. A comparison of birds in T2 vs T3 and T4 showed that bodyweight (BW) and FCR were affected negatively when extra Met was added to the diet. The same effects were seen under thermal-neutral and heat-stress conditions. This trial confirmed that there is a significant betaine x temperature effect on FCR. A significant effect on BW and FCR was demonstrated with the addition of 0.02% betaine to birds’ diets. The results showed that under both thermal-neutral and heat-stress conditions the best performing treatment applied the Met 3200 3100 3000 2900 2800 2700 No Bet 0.2%Bet Req BW, 41d No Bet 0.2%Bet +1.23g/kg MET Thermonatural *Double or triple interactions were not significant, p> 0.10. Heat Stress pBet < 0.001 pMet = 0.25 pTemo < 0.01 pBetxMet = 0.82 No Bet 0.2%Bet Req No Bet 0.2%Bet +1.23g/kg MET Figure 1. Bodyweight (BW) of broilers at 41 days of age. 1.50 1.48 1.46 1.44 1.42 1.40 FCR 0-41, g/g pBet < 0.001 pMet = 0.18 pTemo < 0.01 pBetxMet = 0.99 pBetxTemp = 0.026 No Bet 0.2%Bet Req No Bet 0.2%Bet +1.23g/kg MET No Bet 0.2%Bet Req No Bet 0.2%Bet +1.23g/kg MET Thermonatural *Other double or triple interactions were not significant, p > 0.10. Heat Stress Figure 2. Feed conversion ratio (FCR) of broilers at 41 days of age
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