NUTRITION ▶▶▶
Broilers received either 5% or 10% of the esti- mated daily die- tary DM intake as BSF larvae, either twice or four times a day.
ground pecking and foraging, while their time spent resting was reduced compared to controls. Overall activity – any behaviour except resting and perching while sitting – was lower over several weeks in the control broilers compared to all the BSF groups. Between the larvae groups, the 10% (provided four times a day) broilers were more active after receiving larvae than the 5% (provided twice or four times a day) broilers. From week 2 onwards, the controls showed a decline in ground pecking and total foraging behaviour, while the prevalence of these behaviours remained relative- ly high and constant in all larvae groups. Time spent in a standing position was lower in the controls than in all the BSF groups throughout the study period; the controls spent more time sitting. In general, time spent standing de- creased from week 2 onwards in the controls, and from week 3 onwards in the 5% BSF broilers and from week 4 onwards in the 10% BSF broilers.
Performance The weight gain was generally smaller (but not significantly so in most cases) for the 10% broilers compared to controls. Previous studies suggest that chitin plays a role in the reduc- tion of broiler growth as it is partially digested by broilers. In this study, the researchers found that providing 10% of the dietary DM as BSF larvae twice or four times a day resulted in high larvae intake. They suggest that the digestion-inhibiting effect of chitin could have been strongest in these broilers, resulting in the observed diminished performance. To be
26 ▶ POULTRY WORLD | No. 10, 2020
more specific, the relative consumption of BSF larvae was slightly higher than anticipated (approximately 6% and 12% instead of the expected 5% and 10% of dietary DM) which could have caused a slight imbalance in amino acid uptake, thereby affecting broiler growth. The researchers noted that other studies have found that BSF larvae inclusion in the diet can increase broiler growth and feed intake, and increase the broiler’s T helper cell frequency and serum lysozyme activity, improving nonspecific immune responses. In the current study, the FCR based on DM was higher in the four times a day than in the twice a day frequency, while the FCR of the control group was in between these two.
Amount and frequency The researchers concluded that in their study the largest amount of larvae provided at the highest frequency (10% of the dietary DM as larvae provided four times a day) was most effective in promoting activity and lowering the prevalence of hock burn and lameness, while the final weight of these broilers was not significantly reduced compared to the con- trols. The elevated levels of foraging behaviour and general activity was greatest and most consistent for broilers receiv- ing BFS larvae in the highest amount and frequency. Overall, broilers receiving 5% or 10% of their dietary DM as BSF larvae four times a day showed improved leg health. This study demonstrates that by facilitating natural behaviour and activ- ity through providing larvae as part of the dietary DM can reduce leg health problems and thus benefit broiler welfare.
PHOTO: KOOS GROENEWOLD
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