PSV-11 Significance of specialty protein ingredients in feeding programs for broiler chickens on nitrogen utilization and excretion- A meta-analysis

Abstract The utility of specialty protein ingredients (SPI) in feeding programs for broiler chickens is premised on poor utilization of conventional vegetable proteins (CVP). The SPI includes ingredients of animal origin such as processed animal proteins (PAP), insect proteins (IP) and further processed conventional vegetable proteins (PCVP) characterized with greater concentration of crude protein/amino acids, and low anti-nutritional factors. The objective of this study was to apply meta-analysis approach of published studies that incorporated SPI to provide insights into their effectiveness on nitrogen utilization and excretion in broiler chickens. The data were retrieved from Web of Science, PubMed, ScienceDirect, hand searching and cross-referencing, and resulted in 44 publications meeting inclusion criteria such as being a broiler study and treatments diets being isocaloric and isonitrogenous Model development was performed in PROC GLIMMIX of SAS and treated the study as a random effect. The SPI protein source (PAP, IP, and PCVP), bird age (starter 0 to 14 d, grower 14 to 24 d and finisher 25 to 42 d), nitrogen intake and level were the main X variables of interest, while outcome (Y) variables explored included nitrogen excretion, nitrogen retention, nitrogen efficiency, average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR). To address heterogeneity in sample size and errors between treatment means from different studies, the WEIGHT statement in PROC GLIMIXX was employed to weight variables using the inverse of their squared variance. The inclusion or rejection of models developed was based on the evaluation of root mean square prediction error and concordance correlation coefficient. Comparatively, the slopes of PAP, IP and PCVP (soybean meal) linearly reduced and quadratically (P < 0.05) increased ADG during the starter phase against their respective controls. The extent ADG was greatest with intake of PCVP followed by PAP. During the grower phase, ADG was highest for PAP, followed by IP with PCVP being the least (P < 0.05). However, PCVP had the greatest ADG during the finisher phase (P < 0.05). On nitrogen excretion, provision of PAP during the stater phase increased the nitrogen excretion while it reduced the excretion during the grower and finisher phase (P < 0.05) relative to control. The intake of IP up to 10% inclusion reduced nitrogen excretion only during the starter and grower phase (P < 0.05) when compared with respective controls. The intake of PCVP reduced nitrogen excretion in all growth stages compared with respective controls (P < 0.05). In conclusion specialty proteins (PAP and PCVP) and insect protein at an inclusion level of < 10%, were effective ways of reducing nitrogen excretion while improving growth performance. Combining these strategies may have a synergistic effect.