Effects of silage and haylage on feed intake, growth and health in two meat type chicken genotypes

Sammanfattning: In this project the effect of grass silage and haylage on feed intake (FI), growth and health of two meat type chicken hybrids, Ross 308 and Rowan Ranger were studied. The study was carried out at the Swedish Livestock Research Center, located in Funbo-Lövsta, Uppsala for a period of 42 days. A total of 30 pens were used, 15 pens for each hybrid with eight birds randomly allocated to each pen. Commercial organic feed for the starter period was given at d1-20 in crumble form whereas a pelleted feed was given for the grower period at d20-42. To study the effect of silage and haylage, 15 percent dry matter (DM) of the commercial feed was replaced with either silage or haylage and compared to birds fed only the commercial feed resulting in three treatment groups namely, the control, haylage and silage. Each treatment was assigned randomly to five pens of each hybrids. The overall FI, silage, haylage and pellet intake, bodyweight (BW), feed conversion ratio (FCR) as well as organ weights were measured, gizzard score, sticky droppings, foot pad and litter quality were assessed. The result showed that the overall FI and pellet intake were lower for the chickens fed haylage compared to chickens fed silage and control feed. The roughage intake was higher for chickens fed silage than those fed haylage. The BW for the chickens in the control group were greater than the chickens in the silage group, but lowest with the haylage group. The FCR was poorer for chickens fed silage or haylage compared to chickens fed the control feed. In regards to genoype, Ross 308 chickens had a higher FI, pellet intake, silage or haylage intake and BW compared to the Rowan Ranger chickens whereas for FCR, Ross 308 started off poorly but later on was improved and Rowan Ranger chickens showed the opposite. The result on organ weights showed treatment effect only on the gizzard. The chickens fed silage and haylage had a heavier gizzard compared to chickens fed the control feed. In addition, breed effect was present where Rowan Ranger chickens had a heavier gizzard as well as crop, spleen, liver, small and large intestine than the Ross 308 chickens. However, no genotype effect was seen for the heart, bursa and proventiculus weights. Foot pad and litter quality were not influenced by treatment nor genotype. Sticky dropping was not affected by treatment but at d42 a genotype effect showed Rowan Ranger chickens with inferior condition compared to Ross 308 chickens. Feed treatment had no effect on gizzard score, but a tendency (P= 0.08) of superior condition in Rowan Ranger chickens over Ross 308 chickens was found. In conclusion, feeding diets with 15 percent inclusion of grass silage or haylage decreased growth performance for both Ross 308 and Rowan Ranger hybrids, with a stronger growth reduction with haylage group. However, both these forages did not have any detrimental effect on health parameters.