Growth performance, organ attributes, nutrient and caloric utilization in broiler chickens differing in growth rates when fed a corn-soybean meal diet with multienzyme supplement containing phytase, protease and fiber degrading enzymes.

Growth performance, organ weight, ceca digesta short chain fatty acids (SCFA), jejunal histomorphometry, tibia ash, apparent retention (AR) of components and caloric efficiency were investigated in broiler chicken strains differing in growth rate fed diets with multienzyme supplement (MES). The strains differed in estimated time to reach 2.1 kg BW: 37, 43, 47, and 50 d and were designated C, F, J, and N, respectively. A corn-soybean meal diet was formulated for 2-phase program (starter and grower) and fed without or with MES containing phytase, protease and fiber-degrading enzymes. A total of 640-day-old chicks (42.3 + 0.01 g/bird) were housed in cages (5 cockerels and 5 pullets/cage) and allocated to give 8 replicates/ strain and diet combination. Equal amount of feed was fed based on observed ad-libitum intake of C strain in the starter (d 0-14) and grower (d 15-28). Body weight was monitored, grab excreta samples taken and at completion of allocated feed one bird per cage necropsied for samples. With exception of P, apparent metabolizable energy corrected for nitrogen (AMEn) and ceca digesta acetic acid, there was no (P > 0.05) interaction between strain and MES on examined responses. Strains differed (P < 0.01) on growth, FCR, gizzard weight, tibia ash, breast weight, ceca digesta concentration of lactic, propionic, and isobutyric acid and caloric efficiency. The final body weight (BW) was 1,344, 1,134, 959, and 916 g/bird for C, F, J, and N, respectively. Corresponding caloric efficiency was 4,930, 5,807, 6,680 and 7,199 kcal/kg BW gain, respectively. Birds fed MES had higher BW gain (P < 0.05) in grower phase, larger gizzard, higher AR of CP, crude fat, neutral detergent fiber, and Ca than non-MES birds. In conclusion, growth rate influenced organ attributes, nutrient, and caloric utilization. Enzyme supplementation improved growth in grower phase and nutrient utilization independent of strain, suggesting that effects of feed enzymes are not influenced by inherent growth rate.

Effect of dietary supplementation of ß-mannanase on growth performance, carcass characteristics, excreta microflora, blood constituents, and nutrient ileal digestibility in broiler chickens.

OBJECTIVE: The aim of the present study was to investigate the effects of dietary supplementation of ß-mannanase on growth performance, carcass characteristics, excreta microflora, blood constituents, and nutrient digestibility in broiler chickens. METHODS: A total of 680 one-d-old Ross 308 (as hatched) broiler chickens were used in a 35-d growth assay. Chicks were sorted into pens with 17 birds/pen and 10 pens/treatment. Treatment diets were contained either 44% or 48% crude protein (CP) soybean meal (SBM) with or without ß-mannanase. RESULTS: Using SBM containing 48% CP led to an improvement (p<0.05) in feed conversion ratio (FCR) from d 1 to 14. Addition of ß-mannanase to the diets significantly improved body weight gain (BWG) and FCR from d 1 to 14. During overall experimental period, BWG was affected (p<0.05) by CP level of SBM and inclusion of ß-mannanase, but FCR and feed intake were not affected. Carcass characteristics were not influenced by treatment diets. The results showed that digestibility of dry matter (DM), nitrogen (N), and energy was not affected by CP level of SBM and/or inclusion of ß-mannanase. Among essential amino acids (EAA) apparent digestibility of valine, methionine, and leucine improved (p<0.05) by the addition of ß-mannanase to the diets. The results demonstrated that ileal digestibility of DM, N, and energy was not affected by treatment diets. Among EAA, the ileal digestibility of valine and arginine was higher (p<0.05) in the diets containing 48% CP SBM and/or ß-mannanase. Excreta Lactobacillus count increased (p<0.05) by the addition of ß-mannanase to the diets. Blood urea nitrogen, creatinine, and total protein level were not affected by treatments. CONCLUSION: Feeding chickens with diets containing 44% CP SBM resulted in detrimental effects on growth performance and digestibility of nutrients, but addition of ß-mannanase to the 44% CP diet improved the growth performance of chickens without any effects on carcass characteristics.

Research Note: Comparative gastrointestinal, tibia, and plasma attributes in 48-day-old fast- and slow-growing broiler chicken strains.

Emerging market differentiation for broiler meat from strains exhibiting a range of growth rates is necessitating comparative research on various physiological and production aspects of these strains. The objective of the present study was to compare select gastrointestinal, tibial, and plasma attributes in a sample of 48-day-old (50 male and 50 female) broilers obtained from fast-and slow-growing flocks maintained under similar feed and management regimens. Eight birds were randomly selected from a fast (B; representative of modern commercial strains) and each of the 4 slow-growing strains (SG; D, H, M, and E). The strains differed by estimated time to reach 2.2 kg bodyweight corresponding to 36, 50, 42, 44, and 50 D for B, D, H, M, and E, respectively. Blood samples were collected to determine plasma metabolites, and birds were subsequently euthanized, weighed, and necropsied for gizzard and small intestine weight, jejunal tissue for histomorphology, ceca digesta samples for concentration of short-chain fatty acids (SCFA) and left tibia for ash content. Gizzard was heavier (P < 0.01) for D, H, and M than that for B and E, whereas the small intestine was lighter (P < 0.01) for B, D, and H than for M and E. There were no (P > 0.05) strain differences on SCFA, jejunal villus height and crypt depth, plasma proteins, and electrolytes. Strains D, H, and M exhibited higher (P = 0.01) tibia ash concentration than B; E was intermediate and not different (P > 0.05) from any strain. Specifically, the tibia ash for B, D, H, SG 3, and E were 1.24, 1.44, 1.43, 1.49, and 1.39 g/kg BW, respectively. The B birds showed higher (P < 0.01) plasma concentrations of aspartate transaminase, creatine kinase, lactate dehydrogenase, and creatinine than SG strains. In conclusion, although B and some SG strains had lighter gastrointestinal tract indicative of energy efficiency, higher circulating plasma enzymes in B birds suggested impaired hepatic function. Moreover, lower tibia ash in B suggested disproportionate body mass relative to skeletal support.

Expression of Behavioural Traits in Goldendoodles and Labradoodles.

As crossbred dogs gain in popularity, how they express inherited behaviour traits in comparison to their purebred constituent breeds is of interest. We investigated behaviours exhibited by crossbred dogs by focusing on the popular Goldendoodle and Labradoodle crossbreds and comparing them to their corresponding constituent breeds: Standard and Miniature Poodle, Golden Retriever or Labrador Retriever. The data for this study was provided by 5141 volunteer dog owners who filled out the Canine Behavioural Assessment and Research Questionnaire (C-BARQ) online survey. The survey results were used to analyse breed differences in fourteen representative behavioural trait scores: trainability, stranger-directed aggression, owner-directed aggression, dog-directed aggression, dog rivalry, dog-directed fear, stranger-directed fear, non-social fear, touch sensitivity, separation-related problems, excitability, attachment/attention-seeking behaviours, energy and chasing. As expected from a first-generation crossbred (F1), the crossbreds in our study tend to fall between the two constituent parent breeds with some exceptions. Our results suggest that the F1 Labradoodle differed significantly from one of the pure constituent breeds only in dog rivalry, whereas the F1 Goldendoodle behaviour varied from one or more pure constituent breeds in dog rivalry, dog-directed aggression, dog-directed fear, and stranger-directed fear. These results can help advise future dog owners on behavioural trends for particular crossbreds.