Digestive system development in post-hatch poultry

Effect of enzyme addition on the nutritive value of high oleic acid sunflower seeds in chicken diets

Two experiments were conducted to evaluate the effects of enzyme addition in chicken diets containing high oleic acid sunflower seeds (HOASS). In the first experiment (4 to 21 d of age), enzyme addition (lipase, phospholipase, and a combination of these) was used at the inclusion level of 1 g/kg in diets containing HOASS (250 g/kg) compared with a control corn-soybean diet. Weight gain, feed consumption, relative liver weight, fat digestibility, and amylase, lipase, serum lactate dehydrogenase (LDH), and creatine phosphokinase (CPK) activities were reduced, and feed conversion, relative duodenum, jejunum, ileum, and ceca lengths, plasma uric acid, cholesterol, and glucose concentrations were increased in the unsupplemented HOASS diet compared with the control diet. The addition of enzymes to the HOASS diet increased weight gain, feed consumption, relative pancreas and liver weights, fat digestibility, amylase and lipase activities, plasma uric acid, calcium, serum LDH and CPK, and total protein concentration and reduced feed conversion, relative spleen weight, relative duodenum, jejunum, ileum, and ceca lengths, plasma cholesterol, and glucose compared with the unsupplemented HOASS diet. In the second experiment (0 to 21 d of age), the same enzymes (0.5 g/kg each) were included in diets containing 150 g/kg of HOASS compared with a conventional sunflower meal diet (150 g/kg). The HOASS diet did not affect performance but reduced relative pancreas and abdominal fat weights and relative duodenum and ceca lengths, and increased crude fat, CP, and essential and nonessential amino acid digestibilities (except Ser, which was reduced) compared with the control diet. The addition of enzymes in the HOASS diet increased weight gain, feed consumption, and relative pancreas weight and reduced feed conversion, CP, and essential and nonessential amino acid digestibilities compared with the unsupplemented HOASS diet. In conclusion, the addition of 250 g of HOASS/kg in the diets caused a negative effect on performance, digestive organ sizes, fat and protein digestibilities, and pancreatic enzymes and modified blood parameters. However, the inclusion of HOASS at 150 g/kg improved some of these parameters and amino acid digestibilities. The enzyme addition counteracted some of these effects.

Nutrition of the developing embryo and hatchling

Nutrient needs central to satisfactory egg incubation well-being undergo several major changes from fertilization until the reliance of the chick on feed. Glucose is central, with the initiation of incubation until the chorioallantois accesses O(2) to use for fatty acid oxidation. Nutrient recovery from albumen and yolk is largely commensurate with body assembly through to completion of the embryo by 14 d. Remaining albumen mixes with the amniotic fluid and is orally consumed until initiation of emergence. A portion of the albumen is absorbed by the small intestine to expand body glycogen reserves. The residual not absorbed contains digestive enzyme contributions and enters the yolk sac through its stalk at the jejunum and ileum. Interaction of the albumen-amnion digestive enzyme mixture with yolk sac contents leads to diverse alterations that influence subsequent use of lipids. Rapid removal of very low-density lipoprotein ensues, until pipping with triglycerides, expanding body fat depots while cholesterol deposits in the liver. A concurrent translocation of Ca from shell mineralizes the skeletal system while also crossing yolk sac villi for deposition on phosvitin-based granules accruing in its lumen. Loss of chorioallantois with pipping and the start of pulmonary respiration predispose a dependence on glycolysis to support emergence. Small intestinal villi progressively reorient their enterocytes from macromolecule transfer to competence at digestion and absorption after hatching. Mobilization of body fat complements contributions from the yolk sac to provide fatty acids for generating energy, heat, and water while also combining with hepatic cholesterol for membrane expansion and continued development. Calcified granules evacuate the yolk sac to further skeletal mineralization in the absence of shell contributions. Egg mass, its interior quality, and turning during early incubation directly influence the ability of the embryo to access nutrients and provide resources to support emergence and the transition of the chick to self-sufficiency.

Development of the activities of pancreatic and caecal enzymes in White Roman goslings

1. This study was to investigate the development of the activities of pancreatic and caecal enzymes in White Roman goslings from hatching to 28 d of age. 2. A total of 80 1-d-old goslings were used. At hatching, 3 and 7 d of age, 16 goslings (8 males and 8 females) were used. At 11, 14, 21 and 28 d of age, 8 goslings, 4 males and 4 females were selected. The activities of amylase, lipase, trypsin and chymotrypsin in each segment of the small intestine (duodenum, jejunum, ileum) and their contents and the activity of cellulase in the caecal contents were measured. 3. The specific activity (SA) of amylase in the duodenal mucosa and contents increased significantly both from 11 to 14 and 14 to 21 d of age and declined after 28 d of age. In the jejunum and ileum, there was a significant peak in the SA of amylase in the mucosa in goslings from 7 to 21 d of age. On average, the SA of lipase of mucosa and content in the small intestine was initially low but gradually increased from 14 to 21 and from 21 to 28 d of age. 4. The SA of trypsin in the contents of the duodenum and the jejunum increased both from 7 to 11 and 11 to 14 d of age and there was high activity in the ileal contents from 14 to 21 d of age. From 3 to 14 d of age, the SA of chymotrypsin in the duodenal mucosa significantly increased and peaked. There was a significant peak at 11 d of age in the SA of chymotrypsin in the duodenal or jejunal contents and in the ileal contents at 7 d. The SA of cellulase in the caecal contents increased linearly with age, reaching a plateau at 28 d of age. 5. The rate of activity development varied from hatching to 28 d of age. However, the mean SA of amylase and lipase of intestinal contents reached a peak at 21 d, trypsin and chymotrypsin at 11 d and cellulase at 28 d of age, respectively. The quantitative changes in SA of cellulase, amylase, lipase, trypsin and chymotrypsin increased by about 4-, 3-, 5-, 2- and 3-fold, respectively, in the intestinal content of goslings. Thus, development of proteases in the intestine of goslings peaked more rapidly than amylase, lipase and cellulase during the first 4 weeks.

Effect of age of growing turkeys on nutrient digestibility and energy value of cereal-soybean-based diets

Ileal and total tract digestibility of protein, total tract digestibility of fat and AMEN of cereal-based diets were assayed in growing turkeys at four, seven and 12 weeks of age. Fat digestibility and AMEN improved linearly with age. Total tract protein digestibility improved with age according to a curvilinear trend, while ileal protein digestibility improved from 4-7 weeks of age but decreased from 7-12 weeks of age. It can be concluded that higher AMEN values could be applied when formulating diets for older than for younger turkeys. Regarding protein digestibility more investigation is needed but a possible fall in values after the first weeks of age may be expected.

The Effect of Fat Type, Carbohydrase, and Lipase Addition on Growth Performance and Nutrient Utilization of Young Broilers Fed Wheat-Based Diets

A 2 x 2 x 2 factorial experiment was conducted to evaluate the effects of fat type (beef tallow [50 g/kg diet] or canola oil [50 g/kg of diet]), carbohydrase addition (none or carbohydrases [0.4 g/kg diet]), and lipase addition (none or lipase [0.2 g/kg of diet]) on growth performance and nutrient utilization of male broilers fed a wheat-based diet from 5 to 18 d. The carbohydrase supplement contained xylanase, glucanase, cellulase, and other enzyme activities. The experimental diets were formulated to be suboptimal in major nutrients and each was fed in a mash form to 10 replicate pens of 5 broilers per pen. Body weight gain was not affected by fat type but a poorer feed/gain ratio (P < 0.001) was noted for tallow-containing diets. Regardless of fat type, carbohydrase enzyme supplementation improved (P < 0.001) BW gain and feed/gain ratio. There was no effect of lipase addition on chicken performance and nutrient utilization. When compared with canola oil, tallow-containing diets had a lower (P < 0.001) apparent fat digestibility and consequently a lower dietary AMEn content. Carbohydrase enzyme addition improved (P < 0.001) fat, starch, nitrogen, and nonstarch polysaccharide (NSP) digestibilities in the small intestine, improved AMEn, and reduced (P < 0.001) jejunal digesta viscosity in both fat types. Carbohydrase supplementation increased water-soluble (P < 0.001) and decreased water-insoluble (P < 0.001) NSP concentrations in the small intestine. The interaction between fat type and carbohydrase addition was only significant for fat digestibilities, with greater improvements seen for diets containing tallow. Significant interactions between carbohydrase addition and intestinal segment were noted for fat, starch, nitrogen, and NSP digestibilities, with the enzyme effects being greater in the jejunum than the ileum. It is evident from the present study that an appropriate carbohydrase preparation could eliminate the negative effects of soluble NSP on animal fat utilization in a wheat-based broiler diet.

Response of turkey poults to soybean lectin levels typically encountered in commercial diets. 1. Effect on growth and nutrient digestibility

Lectins are known to bind to the intestinal brush border membrane and induce antinutritional effects such as disruption of the brush border membrane (BBM) and reduced nutrient digestibility in laboratory rodents. Because soybean lectin (SBL) is usually present in poult starter diets, 2 similar experiments with starting turkey poults were conducted to investigate the effects of purified SBL on growth performance and nutrient digestibility. Experimental diets were a corn starch-casein based control (lectin-free) semipurified diet (PD), semipurified diets containing 0.024 or 0.048% soybean lectin (PDL, PDH), and a corn-soybean meal diet (SBD). Experimental diets were fed from hatch to 14 d. Antibodies specific for soybean lectin were detected in the serum of poults fed the PDL and PDH diets, implying that the SBL in these diets remained active in the digestive tract. Poults fed the control PD or SBD grew equally well. The 0.024% SBL level in PDL had no significant detrimental effect on any parameters assessed in the 2 experiments. In contrast, the 0.048% SBL level in the PDH gave inconsistent results for feed efficiency (FE) and brush border enzyme levels. For instance, on d 6 in experiment 2, poults fed the PDH had poorer FE (P < 0.05) compared with the control PD treatment, but had similar FE to poults fed the PD in experiment 1. In conclusion, SBL present at levels up to 0.024% of the diet would not cause antinutritional effect in turkey poults up to 2 wk of age.

Effects of delayed feed intake on body, intestine, and muscle development in neonate broilers

The short-term effects of delayed feeding (DF) for 2 d posthatching were measured in neonate chicks and compared to early feeding (EF). Chicks from 10 independent families were used in this study to determine whether genetic background control of growth may be influenced by EF and DF. Early feeding maintained significant interfamily body weight variations from hatch to 4 d of age, whereas there were no significant differences from 1 d of age when feeding was delayed to 48 h posthatching. These results suggest that posthatching feeding delay may distort genetic selection by masking the expression of genetic potential and disturbing the estimation of chick breeder value. In DF chicks, overall body growth was delayed until the beginning of feeding and body weight at 6 d of age was 25% lower than EF chicks. Availability of feed after the fasting period was not sufficient to compensate for the retardation of weight gain in either body weight or in intestine and breast muscle weight. However, initiation of intestine growth in DF chicks occurred from 1 d of age despite the lack of feeding, whereas feed intake was essential to enhance muscle growth. The potential for protein synthesis was lower in DF than in EF chicks during the first 2 d posthatching (P < 0.001) and then reached similar values after feed intake. These results confirm that initiation of growth in neonate chicks is improved by earlier feeding after hatching. Awareness of changes in overall body weight caused by posthatching food deprivation, especially in the intestine and muscle might help in the development of new diets which could minimize retardation of body weight gain in chicks.

Energy utilization in newly hatched chicks

The changes in body weight and composition were examined in broilers that either had immediate access to feed and water or had not been fed for 48 h posthatch. Chicks without access to feed decreased in BW by 7.8% in the 48 h posthatch, which was equivalent to 5.3 kcal/45 g chick/d. However, during this period the small intestines increased in weight and protein content by 80% or more. The decrease in yolk fat and protein could account for most of the changes in body composition in the feed-deprived chick. In contrast, fed chicks grew by 5 g and used 4.5 kcal/d for maintenance; during this period small intestines increased in weight by 110%. Intestinal absorption of exogenous nutrients was determined from hatch through 4 d posthatch by administration of a bolus of labeled glucose, methionine, or oleic acid, together with a nonabsorbed reference substance. Absorption of fatty acids was more than 80% at hatch and was higher than that of glucose and methionine, which was low especially when the bolus was administered as a solution. Absorption of all components tested increased with age and was more than 80% on Day 4. Duodenal in situ uptake determinations in hatching chicks indicated that uptake of oleic acid was high from yolk and saline solutions compared with glucose and methionine, which exhibited low uptake from yolk but higher uptake from saline solutions. These studies indicate that, although the small intestine has the capacity to absorb carbohydrates and amino acids at hatch, uptake may be dependant on the development of suitable conditions, including sufficient pancreatic and brush border enzymes for digestion and adequate sodium for function of the glucose-sodium cotransporters.