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Description of scholarship program for masters and doctoral students. University of Guelph Agri-Food and Rural Link and OMAFRA

We tested the hypothesis that poultry by-product meal would produce a thermogenic response (an increased requirement for oxygen) resulting in an increased incidence of pulmonary hypertension with right ventricular failure and ascites in commercial broiler chickens.Four treatment groups, each with three replicates of 40 chicks, were fed a commercial broiler starter to day 21, grower to day 35, and the following experimental diets after day 35: group 1, commercial chicken broiler finisher; group 2, commercial chicken broiler finisher with poultry by-product meal added to replace part of the soyabean meal; group 3, commercial chicken broiler finisher with poultry fat added to replace the animal-vegetable (AV) fat; group 4, commercial chicken broiler finisher with both poultry by-product meal and poultry fat added to replace soyabean meal and AV fat. On day 35, pen temperature was reduced to 15 degrees C, and on day 42 to 12 degrees C.Mortality from ascites between days 35 and 56 was 11(9%) in group 2, 5(4%) in group 4 and 3(2.5%) in groups 1 and 3 The incidence of pulmonary hypertension, as measured by an increased right ventricle: total ventricle (RV:TV) ratio (RV:TV0.249) at processing on day 57, was higher in the groups receiving poultry by-product and poultry fat: 27(22.5%) in group 2, 26(21.7%) in group 3, and 20(16.7%) in group 4 compared to that of the controls 12(10%).

Trials were conducted to investigate the effect of species, fish size and dietary protein/energy ratio on the efficiency of feed use for growth (biomass) in salmonids. To gain insight on efficiency of this conversion and how the above factors affected the efficiency of this conversion, several approaches were used. First, the efficiency of conversion of feed to growth was investigated by simple growth assays. Weight gain, feed efficiency (weight gain/feed intake) and composition of the gain was species specific. Diet composition had no affect on weight gain or composition of gain. However, feed efficiency decreased (P < 0.05) with decreasing digestible protein/digestible energy ratio (DP/DE) for juvenile lake trout, Atlantic salmon and chinook salmon and rainbow trout, while no effects were observed for postjuvenile fish (P > 0.05). There were species differences (P < 0.05) in nutrient and energy digestibility. Digestible nitrogen (DNRE) and energy retention (DERE) efficiency also differed among species (P < 0.05) and diet affected DNRE (P < 0.05) but not DERE (P > 0.05). The energetics of growth was investigated by empirical approaches of partitioning of metabolizable energy (ME) utilization for non-productive (maintenance) ' vs.' productive aspects of growth. The maintenance requirements (MEm) and the cost of growth (kg) and of protein (k p) and lipid deposition (kf) were estimated by either linear or non-linear regression models as well as by a multivariate analysis. K g averaged 0.63, irrespective of species, fish size and diet. K p varied from 0.53 to 0.81 and it was higher (P < 0.05) for post juvenile salmon compared to post juvenile trout and were not affected by diet (P > 0.05), while kf varied from 0.81 to 0.94, irrespective of species, fish size and diet. Using respirometry, estimates of total heat production (HE), basal metabolism (HeE) and heat increment of feeding (HiE) were obtained and species variation investigated. Estimates of HeE and HiE were used to validate MEm and kg, and reasonable degree of agreement was obtained. It is concluded that the efficiency of feed use for growth in salmonids differed among species and fish sizes used in these studies.

AMEn of whole and ground flaxseed introduced gradually or abruptly to a diet, was variable. AMEn of flaxseed was increased (P < 0.05) when fed in a pelleted diet compared to mash. Extruding flaxseed increased (P < 0.05) diet AMEn while subjecting a diet to expanding and pelleting reduced (P < 0.05) AMEn. Hens fed the expanded and pelleted diet deposited less (P < 0.05) DHA and LNA in their eggs compared to a pelleted diet. The addition of enzymes to a flaxseed diet did not increase its AMEn; however, egg deposition of LNA and DHA were increased (P < 0.05). Fatty acid profiles of flaxseed showed that the fatty acid content of flaxseed is consistent. Egg production parameters were not (P > 0.05) affected by feeding flaxseed; however, feed intake, body weight, and yolk weight were reduced (P < 0.05). Total egg n-3 fatty acids were not different (P > 0.05) between strains. Flax-fed hens had greater (P < 0.05) incidence of liver hemorrhage.

Experiments were conducted with the objective of improving fat digestion in poultry through the use of supplemental lipase enzymes and detergent. Although the addition of lipase enzymes had resulted in improving diet ME with a significant increase in apparent fat digestibility, this was combined with a distinctive pattern of low feed intake, low body weight gain and reduced fecal soap formation. Both histological examination of the small intestine and a cineradiographic study of birds fed diets supplemented with lipase enzyme showed that the enzyme does not affect the gut structure nor does it adversely affect gastric motility. In general the use of detergent had no significant effect on any of the measurement criteria tested. At this time it appears that commercial pancreatic lipase products induce anorexia in some way.

This thesis examines the effects of feeding level, water temperature and diet composition on growth and efficiency of feed utilization by rainbow trout and Atlantic salmon. Trout were fed either to near-satiation (NS) or at 85 (R1) or 70% (R2) of the amount of feed consumed in the previous week by NS fish at 6, 9, 12 and 15$\sp\circ$C. The total feed intakes were on average 76% (R1) and 65% (R2) of that of the NS group. Salmon reared at 15$\sp\circ$C were fed three diets with different protein/energy ratios at either 100% or 85% (feed requirement model). In both species, reducing feed allocated significantly reduced body weight gain. Feed efficiency, carcass composition, nitrogen, phosphorus and energy retention efficiencies (% DE) and waste outputs were not affected by feeding level or water temperature. The apparent digestibility of dry matter, nitrogen and energy of the diet significantly increased with increasing water temperature. Increasing the DE of the diet significantly increased feed efficiency and reduced total solids, total phosphorus and solid nitrogen waste outputs (g/kg gain). Efficiency of metabolizable energy utilization for growth (K$\sb{\rm pf}$) and the ratio of energy deposited as protein vs. lipid, were not affected by feeding level or temperature, but they were affected by diet composition.