Evaluating Environmental Enrichment Usage by Broiler Breeders During the Rearing Period

Abstract

The impact of environmental Enrichments (EE) on broiler breeder behavior is an undeveloped field that needs to be further studied. This research aims to improve the understanding of abnormal repetitive behavior (ARB) performance and behavioral interactions with EE of broiler breeders under feed restriction during rearing phase. In the first study, 424 pullets (Ross 308 AP) and 84 cockerels (Ross 344) were randomly allocated in 8 large pens (4.57 m x 1.82 m; n=46 chicks) for pullets and 14 small pens (1.21 m x 1.82 m; n=12 chicks; 7 pullet pens and 7 cockerel pens). At 40 days of age, two enrichments (EE), shaving bags (SH) and pecking stones (PS) were added simultaneously to the pen. Each small pen received 1 SH and 1 PS, while each large pen received 3 SH and 3 PS. Behavioral observations were performed for ARB on 11 nonconsecutive days, five days before, five days after, and the day of the EE placement. This behaviors were classified as repetitive pecking to the feeder (RPF), repetitive pecking to the waterline (RPW), repetitive pecking other (RPO), feather licking, feather pecking, and pacing. Two two-way ANOVAs (PROC GLIMMIX, Poisson distribution) were performed for effects of enrichment introduction in sex or group size. With means separation via Tukey Kramer. A difference was found between sexes, with cockerels increasing RPF performance after the EE introduction (24.63 vs. 27.4; P < 0.01), while the behavior decreased in small groups of pullets (30.26 vs. 24.61; P < 0.01). Large group of pullets also performed more RPF (27.63 vs, 33.73; P < 0.01) after introducing EE. Feather licking was performed in small quantities for cockerels before and after EE but did reduce with EE placement (0.35 vs. 0.02; P=0.02). Similarly, pullets performed less feather licking after EE regardless of groups size; small group (9.4 vs. 7.41; P=0.02), and large group (20.77 vs. 12.1; P=0.02). The performance of RPO was pullets before and after EE placement, had a value of (6.4 vs. 1.54; P < 0.01) in small groups and (14.03, 0.87; P < 0.01) in large groups. Feather licking and pacing did not differ in performance. These results indicate that is important to consider sex and group size as a factor when implementing EE during rearing. Study 2 evaluated ARB performance plus EE usage during 4-3 feeding regimen within small pens of cockerels and pullets. The 4-3 feeding regimen was fully implemented at 5 weeks of age (WOA). Behavioral observations were performed two days per week (days on and off-feed), every other week from 6 to 14 WOA. Two behavioral categories ABR and EE engaging behaviors were observed. To analyze ARB and EE behaviors, two-way ANOVAs (PROC GLIMMIX) were performed for effects of feeding day and sex or time of day (TOD) on every category of behavior. A spearman correlation (PROC-CORR) was used for correlations ARB and EE engaging behaviors. Bird behavior differed from on-feed vs. off-feed days. In cockerels, RPF performance was lower during off-feed days compared to on-feed (15.17 vs. 32.74; P < 0.01), as was RPW (2.34 vs. 3.88; P=0.04), while RPO was higher on off-feed days (5.34vs 0.41; P=0.03). In pullets, the frequency of RPW performance was higher for on-feed days (2.06 vs. 3.97; P=0.04), but feather licking performance was higher on off-feed days (14.94, 8.61; P=0.04). While for the EE engaging behaviors, both pecking at the PS and SH were performed more by cockerels during off-feed days (5.63 vs. 15.43), then by pullets during off-feed days (3.71 vs. 12.57), pullets on-feed days (1.97 vs. 5.76), and cockerels on-feed days (1.57 vs. 5.31; P=0.03 and P=0.02, respectively). Spearman correlation showed that RPF and pecking at the SH have a strong negative correlation (-0.71; P < 0.01). These results show that ARB performance by broiler breeder behavior differs by both sex and feeding regimen. EE may help to direct some ARB linked to feeding frustration to explorative behaviors with EE. Overall, these studies conducted during different periods of EE introduction highlight the importance of considering sex, group size, and feeding schedule when evaluating the effects of EE in broiler breeders’ behavior.