1. Body weight and the weight of the digestive organs and activities of some digestive enzymes were determined from hatching to 23 d of age. 2. Relative daily growth rate peaked at 11 d of age (22% gain/d) and then decreased gradually. 3. The vitelline residue was decreased rapidly from 4.6 g at hatching to negligible values from 4 d of age. 4. Maximal allometric growth of the pancreas and small intestine was 4-fold and that of liver 2-fold greater than that of the body. 5. Activities (units/kg body weight) of the digestive enzymes measured in the pancreas and intestinal contents increased with age. In the pancreas maximal values were attained on day 8 for amylase and lipase and 11 for trypsin and chymotrypsin. In the small intestine maxima were attained on day 4 for lipase, 11 for trypsin and chymotrypsin and 17 for amylase. 6. The development of secretion of digestive enzymes in the post-hatched chick could be a limiting factor in digestion and subsequently in food intake and growth.

1. The 'extra caloric' effect of added soyabean oil, as reflected in improved body weight gain, food utilisation, metabolisable energy or net energy deposition in the body was determined. 2. Two diets were formulated to contain 12.1 MJ/kg, one with no added fat and the second with 30 g/kg soyabean oil. Addition of oil improved body weight gain by 6.9% (P < 0.05). Two other diets were formulated to contain 13.0 MJ/kg, one with 30 and one with 60 g/kg added soyabean oil bringing the total fat in the high energy, high fat diet to 84 g/kg. Addition of oil in this case improved weight gain by only 3.4% (ns). Addition of soyabean oil increased the apparent digestibility of total dietary fat and reduced that of starch. 3. The effect of soyabean oil supplementation on mash diets at both energy concentrations or to the pelleted diet (formulated to contain 12.1 MJ) on AMEn was consistently positive although not significant. Addition of soyabean oil improved net energy deposition in the body by 17% within the 12.1 MJ/kg diets, (30 g/kg soyabean oil addition) (P < 0.05), but was reduced by 2% (ns) within the 13.0 MJ/kg diets (60 g/kg soyabean oil addition). 4. Supplementing a pelleted diet formulated to contain 12.1 MJ/kg, with 30 g/kg soyabean oil, improved food utilisation (P < 0.05). The 'extra caloric' effect of added soyabean oil, defined as the beneficial effect of the oil above that predicted from its energy value, varied according to the parameter chosen to express this effect and was influenced by the concentration of added soyabean oil and the dietary energy.

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Summary ― Glucose metabolism was studied in ewes fed 800 g chopped alfalfa hay (H) or 400 g alfalfa hay and 400 g corn grain given in whole (HWC), ground (HGC) or extruded (HEC) form. Daily intake of metabolisable energy and crude protein were: 5.8 MJ, 109 g; 9.0 MJ, 84 g; 9.5 MJ, 84 g and 8.5 MJ, 88 g in H, HWC, HGC and HEC, respectively. In situ ruminal degradability ranked whole, ground, and extruded corn in ascending order. Ruminal pH and concentration of acetic acid were lower and of propionic acid higher (P < 0.05) in HEC than in HGC and HWC groups. Plasma level of glucose (P < 0.10), insulin (P < 0.05), and the ratio of insulin to non-esterified fatty acids (NEFA) (P < 0.01 ) were higher in HEC than in other groups. Glucose irreversible loss (GILR) and entry rate (GER), recycling (GRec)

The objective of the present study was to evaluate the effect of degree of saturation of fat incorporated into broiler diets on performance and body fatty acid (FA) profile. The various degrees of saturation were achieved by using regular soybean oil (SO) and hydrogenated soybean oil (HSO), mixed at different proportions. The work was carried out on commercial broilers (Experiment 1) and on lines of chickens divergently selected for high (HF) or low (LF) abdominal fat (Experiment 2). Daily BW gain and gain:feed ratio increased and the amount of feed intake decreased as the dietary fat saturation decreased. Digestibility of total fat and of each of the FA was lowest in the HSO group and reached maximal values when 23% or more of the added oil was SO. The AMEn values of the diets were almost parallel to fat digestibility. The performance of the HF and LF chickens was affected by the degree of saturation similarly to that observed for the commercial stock. The degree of dietary fat saturation had very little effect on saturated FA (C16:0 and C18:0) in body lipids, reduced the level of monoenoic FA (C16:1 and C18:1), and raised that of polyunsaturated FA (PUFA) (C18:2, C18:3, and C20:4). Monoenoic FA were higher, whereas PUFA were lower in the HF than in the LF line. The improved AMEn in diets containing unsaturated fat is probably due to higher fat digestibility, direct deposition of PUFA in body lipids, and lower lipogenesis, associated with lower heat production.

Low subcutaneous adipose deposits on kid carcasses reduce their commercial value. Thus, two experiments were conducted to determine how lipid supplementation can increase fattening in Alpine male kids.In experiment 1, 12 kids received individually, ad libitum a milk replacer (15 % W/V) containing 15.9 (group 1) or 27.0 % (group 2) of fat (especially tallow fat)/DM, from 1 week of age until slaughtering at 7 weeks. In experiment 2, 14 kids were given the same milk replacer (21.5 % fat/DM) until weaning at 6 weeks and from 4 weeks until slaughtering at 14 weeks of age, water, lucerne hay and concentrate were offered ad lib. Concentrate pellets were based on cereals and soyabean-oilmeal in group 3 and on the previous milk replacer powder in group 4. In experiment 1, the level of dry matter intake was higher (6 % : NS) in group 1 than in group 2, but the growth rate was not affected, 213 and 221 g/d (respectively for groups 1 and 2).Body fat of group 1 was the least developed in offals (163 vs 224 g P : NS, 89 vs 161 g P < 0.05, 147 vs 184 g P < 0.10, 13.1 vs 19.7 g P < 0.05 respectively for omental, perirenal, mesenteric and pericardic adipose tissues) and in intermuscular leg adipose tissue (55.8 vs 69.4 g P < 0.10) but there were no differences in the two groups for subcutaneous leg and sternal adipose tissues.During the first 3-week-post weaning period of experiment 2, the level of dry matter intake was lower in group 3 than in group 4 on account of the concentrate intake. In the next period, until slaughtering, the intake of concentrate was similar in the two groups but the hay intake was higher in group 3 than in group 4. Overall growth rate of this post-weaning period was lower in group 3 (185 vs 218 g/d P < 0.10). As

1. Male broilers selected for high (HF) or low (LF) abdominal fat were fed from 8 to 53 d of age on diets containing different concentrations of protein: according to N.R.C. (1984) recommendations (IP), 14% lower (LP) or 14% higher (HP). 2. The growth of LF birds fed on the LP diet was depressed until 35 d of age, but did not differ from the other groups later on. 3. The HF birds had heavier adipose tissues (AT) (g/kg body weight) than the LF birds. Significant line by diet interactions indicated a difference in magnitude of the response of the lines to dietary protein content. 4. Fat concentration of the AT and skin was higher, and in the tibia lower in the HF than in the LF birds. The fat concentration in liver and in breast muscle was not affected by line or by diet. 5. The ratio of saturated plus monoenoic fatty acids to polyenoic fatty acids, considered as an index of fat synthesis, was higher in the abdominal adipose tissue (AAT) of HF compared with LF birds. In AAT, liver and in breast muscle, this ratio was inversely related to dietary protein content.