Effect of dietary lipase enzyme on gut morphology, gastric motility, and long-term performance of broiler chicks

Three experiments were conducted to test a previously described anorexic effect of graded dietary supplements of Pancreatic lipase enzyme on gut structure, gastric motility, and long-term performance of broiler chicks. In Experiment 1, dietary Pancreatic enzyme was used at graded levels of 0, 0.214, 0.429, 0.643, 0.857, and 1.071% to test the effect of this enzyme on gut structure, whereas Experiment 2 was designed to test its effect at 0, 0.268, 0.536, 0.804, 1.071, and 1.339% on gastric motility. The histological examination of the small intestine and a cineradiographic study of birds fed diets supplemented with lipase enzyme failed to detect any difference in gut structure, and there was no apparent adverse effect on gastric motility. Experiment 3 was conducted to test the effect of graded supplements of Pancreatic enzyme on performance of 300 male broiler chicks raised for 6 wk to determine whether the enzyme had any long-term effect on performance characteristics, especially feed intake. Only starter diets (0 to 21 d) were supplemented with 0, 0.375, 0.750, or 1.125% enzyme, and each diet was represented by three replicate pens of 25 male chicks each. Subsequent diets did not contain any enzyme. During the first 3 wk, increased dietary concentration of lipase enzyme caused a linear reduction of feed intake and body weight gain (P < 0.01). At 21 d the percentage weight of the liver was significantly greater with 1.125% enzyme (P < 0.01). However, added enzyme had no effect on 21 to 42 d or 1 to 42 d growth or feed intake (P > 0.05) or on the size of any internal organs examined at 42 d. Pancreatic enzyme has previously been shown to improve fat digestion and increase diet AMEn for young chicks fed animal-vegetable blended fats. These positive effects, however, are associated with marked anorexia, and from the present study, it seems that this effect was not related to physical changes in gut histology or in prolonged digesta transit time.

Endogenous gut nitrogen losses in growing pigs are not caused by increased protein synthesis rates in the small intestine

The purpose of this study was to establish, using a flooding dose of L-[ring 2, 6-(3)H] phenylalanine, whether feeding pigs diets that induce high endogenous gut nitrogen losses (ENL) also increases protein synthesis rates in (PSR) the visceral organs. Twelve 18-kg Yorkshire barrows with catheters in the right and left jugular veins were fed for 3 wk either casein-cornstarch- (CC) or barley-canola meal- (BCM) based diets formulated to a similar digestible energy /crude protein ratio and designed to induce either low or high ENL, respectively. Pigs were infused with 10 mL/kg body weight of a 150 mmol. L(-1) phenylalanine solution containing 230 MBq. L(-1) labeled phenylalanine for 12 min and killed 20 min later. Plasma phenylalanine specific radioactivity (SRA) rose to a plateau value within 3 min of starting the infusion and did not change (P > 0.10) thereafter. Fractional rates of protein synthesis (K(s), %/d) based on SRA in plasma- or intracellular-free phenylalanine did not differ (P > 0.10) in all tissues except pancreas (P < 0.05). Diet affected K(s )in liver (P < 0.01) and colon (P < 0.05) but not in pancreas, duodenum, jejunum and cecum. Based on plasma-free phenylalanine SRA, liver K(s)were 85.4 +/- 11.0 vs. 60.5 +/- 5.2 (mean +/- SEM) in CC- and BCM-fed pigs, respectively; these values were 82.3 +/- 4.7 vs. 98.2 +/- 5.8 in the colon. The absolute amount of protein synthesis (g.d(-1)) was higher in the liver (P < 0.05) and pancreas (P < 0. 05) of the CC pigs compared to BCM pigs. No dietary effects were observed in all other organs (P > 0.10). The present results suggest that feeding growing pigs a BCM diet that induces high ENL does not affect PSR in the small intestine of growing pigs from which >50% of ENL originates.

The effect of intermittent lighting on metabolizable energy intake and heat production of male broilers

Experiments were conducted to compare the effects of an intermittent lighting (IL) schedule with repeated cycles of 1 h light and 2 h darkness with a continuous lighting (CL) schedule on the performance, ME intake, and heat production of male broiler chickens. Body weight gain and feed intake were temporarily reduced after the changing from CL to IL; however, they were significantly higher in IL vs CL chickens during the subsequent period of 3 to 6 wk of age. The IL chickens exhibited a higher ME intake at 6 and 8 wk of age than did CL chickens. Total heat production in IL chickens was higher than for CL chickens, although heat production during the dark period was less than that during the light period for IL chickens. The higher feed intake observed in IL chickens appears to explain the superior body weight gain in IL broilers in simple terms.

The effect of feed deprivation and subsequent refeeding on the bone characteristics of aged hens

In an attempt to improve skeletal integrity of older caged laying hens, birds were held without feed for 4 to 8 d and then refed. Feed deprivation caused an immediate loss in breaking force of the tibia (P < 0.05). Although bone strength increased during subsequent refeeding, values did not return to prefast levels (P < 0.05). Feed withdrawal did cause a reduction in modulus of elasticity of the tibia (P < 0.05), which is a potential benefit for bones that are more resilient to damage; this characteristic was maintained through 30 d of feeding. Histological examination of the tibia hinted at some bone remodelling during refeeding following withdrawal, although the magnitude of these changes was of limited biological significance. These data suggest that simple feed withdrawal for 4 or 8 d is insufficient to bring about a meaningful improvement in skeletal integrity of the older caged laying hen.

Evaluation of dietary supplements of lipase, detergent, and crude porcine pancreas on fat utilization by young broiler chicks

The purpose of Experiment 1 was to improve the digestibility of fat through the use of supplemental lipase enzymes. A 2 x 3 factorial arrangement of treatments involving two levels of animal-vegetable blend fat (AV) (4 and 8%) and three enzyme treatments, namely none; Pancreatic, 0.714%; and Pancreatin, 0.714%, were randomly allocated within a battery brooder. There was an increase in diet ME and apparent fat digestibility when Pancreatic and Pancreatin enzymes were used (P < 0.01). However, both enzymes caused lower feed intake and lower BW gain (P < 0.01). In Experiment 2, Pancreatic enzyme was used at graded levels of 0, 0.214, 0.429, 0.643, 0.857, and 1.071%, involving 4% dietary AV fat. The ME values were greater as the enzyme level increased (P < 0.01). However, as found in Experiment 1 lower feed intake and BW gain were observed with all enzyme levels compared with the control group. There was a linear effect on feed intake and BW gain (P < 0.01) and a quadratic effect on apparent fat digestibility (P < 0.05) and feed utilization (P < 0.01). Experiment 3 was designed to test the effect of Pancreatic enzyme at 0 or 1.339% in combination with two levels of detergent, namely 0 and 10% (with 4% added AV). The detergent used consisted of a mixture of 95% Span 60 and 5% Tween 60. In general, there was no significant effect of detergent (P > 0.05). Experiment 4 was conducted to test the effect of supplementation of graded levels of ground crude porcine pancreas at 0, 0.321, 0.535, 0.750, 0.964, 1.178, or 1.392% of the diet on performance of male broiler chicks to confirm the anorexic effect caused by supplementing with Pancreatic enzyme. In general, there was no significant effect of feeding crude porcine pancreas on the performance of male broiler chicks (P > 0.05). In these studies, lipase enzymes improved fat digestion, although it is suspected that associated reduced feed intake may be associated with contaminants such as cholecystokinin hormone.

Effect of phytase enzyme on dietary nitrogen-corrected apparent metabolizable energy and the ileal digestibility of nitrogen and amino acids in broiler chicks

The effect of phytase on the performance, AMEn, and the ileal digestibility of N and amino acids was investigated in a 15-d trial using day-old male broilers with diets that were low in Ca (0.9% for control and 0.79% for phytase treatment) and available P (AP; 0.45% for control and 0.35% for phytase treatment). The assayed dietary phytase activity of crumble diet was 1,149 phytase unit (FTU)/kg. Chromic oxide was added to the diets to estimate ileal digestibility of N and amino acid. Excreta were collected from Day 12 to 15 to estimate AMEn. Weight gain, feed intake, and feed:gain of chicks fed phytase using diets with low Ca and AP were comparable with those observed for chicks fed more normal levels of Ca and AP. The diet with supplemental phytase had a higher AMEn (P< or =0.01) compared with the control diet. Chicks fed phytase had higher digestibilities for Val, Ile, nonessential amino acids (P< or =0.05), and total amino acids (P< or =0.01).

The effect of dietary supplementation with 1,25-dihydroxycholecalciferol or vitamin C on the characteristics of the tibia of older laying hens

Seventy-two-week-old Leghorn hens were fed a conventional corn-soybean meal diet, or comparable diets either devoid of all supplemental vitamins, or with additions of 5 microg/kg 1,25-dihydroxycholecalciferol [1,25(OH)2D3], or 100 ppm vitamin C. The diets were fed for up to 30 d, with periodic observation on bone characteristics of selected birds. With a vitamin-deficient diet it took 30 d to realize significant reductions (P < 0.05) in bone breaking strength and these birds had less bone ash as early as 15 d (P < 0.05), although bone calcium content was not affected. Adding 1,25(OH)2D3 to the diet caused an increase in bone breaking strength after 15 d (P < 0.05) in the vitamin-deficient birds, although no difference was seen after 30 d. This increase in bone strength was associated with increase in bone cross-sectional area. Vitamin C generally had little effect on bone characteristics of the bird. These results suggest that there is little bone remodeling of older laying hens in response to short-term feeding of 1,25(OH)2D3 or vitamin C.

Effect of housing birds in cages or an aviary system on bone characteristics

Sixty-nine-week-old brown egg layers were either maintained in cages or moved to a litter-floored aviary system. After 10 or 20 d, birds were selected at random from within each environment, and their tibiae removed. After drying, bones were measured and then subject to various physical measurements of strength and elasticity. Bone ash and bone calcium content were also measured. Birds maintained in an aviary initially had stronger bones as measured by force (P < 0.05). After 20 d in an aviary, birds had stronger bones, as assessed by force, than their contemporaries maintained in cages. This same relationship was seen in measures of bone stress (P < 0.05). After 20 d in the aviary system, previously caged birds had bone ash values that were intermediate between birds held only in cages or the aviary (P > 0.05). Bone calcium content was not influenced by the bird's environment. It appears that the skeleton of caged birds can be affected by providing them with an environment that allows opportunity for increased static and dynamic loading of the bones.

Organoleptic evaluation of eggs produced by laying hens fed diets containing graded levels of flaxseed and vitamin E

Eighteen-week-old laying hens were fed diets containing 0, 10, or 20% ground flaxseed and 10 or 100 IU vitamin E/kg diet, in a factorial arrangement. When birds were 60 wk of age, eggs were collected from various treatments and used in taste panel studies. All studies involved freshly boiled eggs. In Experiment 1, four separate panels were conducted to obtain information on egg aroma, egg flavor, presence of any off-flavor, and overall acceptability of the egg. Pooled data showed a very significant difference among panelists for all attributes tested (P < 0.01) and off-flavors were detected in eggs from hens fed 10 and 20% flaxseed with 10 mg vitamin E/kg. In Experiment 2 panelists were asked to evaluate egg aroma, yolk flavor, and overall acceptability in eggs from birds fed the lowest level of vitamin E with 0 or 10% flaxseed, and birds fed 20% flaxseed and 10 or 100 mg vitamin E/kg. The highest ratings for egg aroma, yolk flavor, and overall acceptability were for the control eggs. There was a significant reduction in overall acceptability as flaxseed concentration increased (P < 0.05) and an interesting and significant (P < 0.05) decline in overall acceptability for birds fed 100 vs 10 IU vitamin E/kg diet in eggs for birds fed 20% flaxseed. In a third study, there was an indication of preference for eggs from birds not fed flaxseed, when the diet contained 10, rather than 100 IU vitamin E/kg diet. These data suggest that high (> 10%) levels of flaxseed used in the bird's diet will result in some decrease in overall egg acceptability as assessed by aroma and flavor. These effects seem to be accentuated by using high levels of vitamin E in the bird's diet.

Nuclear magnetic resonance imaging as a tool to estimate the mass of the Pectoralis muscle of chickens in vivo

1. Nuclear magnetic resonance imaging (MRI) was used to assess the advantages of the technique in determining the size (volume) and shape of the Pectoralis muscle (Pectoralis major and minor) in broiler chickens, non-invasively and in vivo. 2. The imaging was performed using a Spectroscopy Imaging System 2.0 Tesla/31 cm bore imaging spectrometer. Three-dimensional reconstruction of transverse images was used to estimate the size of the Pectoralis muscle of chickens ranging in body weight from 362 to 1643 g. 3. Regression analysis resulted in R2 values of 0.92 and 0.99 for the relationship between Pectoralis muscle weight, body weight and muscle volume, respectively. 4. It is concluded that MRI and 3-dimensional image reconstruction may be used to estimate the Pectoralis muscle size and shape. This may be readily extended to monitor the influence of various factors on the growth and development of specific organs and tissues in the body.

Size and components of poult yolk sacs

An experiment was designed to examine the effects of strain of turkey, size of egg, and stage of embryonic development on yolk and yolk sac utilization. Sixty eggs from Nicholas and British United Turkeys of America (BUTA) breeders were selected within each of the weight categories 70 to 76, 80 to 86, and 90 to 96 g. These eggs were incubated under commercial conditions, and eggs selected at 0 or 25 d incubation, at hatch, and 24 h posthatch and yolk and embryos were weighed and assayed for fat, protein, or fatty acids. Yolk weight declined from 23.7 g at setting to 4.66 g at hatch and subsequently to 2.87 g, 24 h posthatch. Yolk weight was affected by strain and egg weight and a number of significant (P < 0.05) interactions were observed. Nicholas strain birds yielded the largest yolks, with the strain difference being most pronounced for the largest egg weight category. Larger turkey eggs contained more water, such that at 24 h posthatch there was double the amount of residual water in the yolk sac. At 24 h posthatch, the Nicholas poults had more water available in the residual yolk. Egg weight had little effect on lipid reserve in the yolk or yolk sac after 25 d incubation. Fatty acid profile of yolk lipids changed little throughout incubation. A number of strain differences are seen in fatty acid profile in the yolk during utilization, although these are quite small and may not be of sufficient magnitude to account for any strain differences seen in early poult viability or growth. Data suggests that the poult and chick may be different in metabolism of various lipid fractions, although in general nutrient utilization by the poult follows a fairly well established sequence of events.

A problem with characteristics of the thin albumen in laying hens

Industry observations indicate that a proportion of shell eggs exhibit an uncharacteristic spreading of the thin albumen when they are broken-out for fast-food preparation. Because the height and characteristics of the thick albumen are unaffected, the eggs are classified as Grade A. Preliminary observations discounted effects of egg storage or contaminated feed. Two experiments were conducted with Leghorn hens over a full laying cycle, and involved different levels of protein (14, 16, 18, or 20%) and associated amino acids, or different degrees of acid-base balance (150, 200, 250, or 300 mEq/kg). In each trial, treatments were represented by eight replicate groups of four adjacently and individually caged birds. Diet treatment had some effects on conventional production parameters, although there were no major effects on the area of the thin albumen produced when eggs were broken out. In Experiment 1, birds fed the highest level of protein produced eggs with the smallest thin albumen area; however, there was considerable bird to bird variation with thin albumen area varying from 69 to 122 cm2. Ten birds with compact (x 69 cm2) and 10 birds with spreading thin albumen (x 112 cm2) were inseminated with semen from a single, unrelated rooster. Offspring from these hens had significantly (P < 0.01) different thin albumen characteristics corresponding to those of their dams. Offspring producing eggs with the spreading thin albumen had the thickest eggshells as assessed by deformation measurement (P < 0.05). It is proposed that the excessively large spreading thin albumen area is caused by eggs spending more time in the shell gland.

Intraneural lidocaine uptake compared with analgesic differences between pregnant and nonpregnant rats

BACKGROUND AND OBJECTIVES

Pregnant patients need less local anesthetic in order to obtain the same quality of functional block as nonpregnant patients. Our goal was to demonstrate a similarly increased functional susceptibility to local anesthetics in the awake pregnant rat during peripheral nerve block and to investigate the pharmacokinetic and/or pharmacodynamic mechanisms responsible for this phenomenon.

METHODS

Radiolabeled lidocaine uptake was determined in vivo during sciatic nerve block with 0.1 ml of 1% lidocaine in the nerves of nine pregnant and five nonpregnant female rats and six male rats at the return of deep pain sensation, assessed by withdrawal of the hindlimb from a brief squeeze of a digit with serrated forceps. During recovery from complete functional block, the time at which deep pain returned and the amount of lidocaine in the nerve at that time were compared among the three groups of rats. Lidocaine content was also determined in vitro after exposure of ensheathed sciatic nerves from pregnant and nonpregnant rats to a 0.2% lidocaine bath for specified times.

RESULTS

Full block of function developed in all groups within 6 minutes of the lidocaine injection and lasted significantly longer in pregnant rats than in nonpregnant and male rats (49.0 +/- 3.3 vs 34.0 +/- 3.1 and 32.0 +/- 1.3 minutes mean +/- SEMI, respectively. At the time of deep pain return, the intraneural lidocaine content of pregnant rats was significantly lower than that of nonpregnant and male rats (2.2 +/- 0.25 vs 3.9 +/- 0.7 and 3.7 +/- 0.6 nmoles/mg of wet nerve, respectively). No difference in lidocaine uptake kinetics between P and NP nerves was observed in vitro.

CONCLUSIONS

Block of peripheral neural function is prolonged in pregnant rats, and lidocaine content in the nerve is lower at a specific stage of neural block. These results are consistent with a pharmacodynamic mechanism for increased susceptibility to lidocaine neural block during pregnancy.

Nutrition of the broiler chicken around the period of compensatory growth

Three experiments were conducted with cage-reared broilers to 21 d following nutrient restriction from 6 to 12 d age. In Experiment 1, birds were full-fed from 6 to 11 or given 50% of ad libitum intake on a daily basis, or 100% of ad libitum intake on a daily basis when the diet was diluted 50% with oat hulls. Birds were not able to fully recover body weight depression by 21 d, although birds previously restricted, by whatever method, were more efficient (P < 0.01) in overall energy intake:body weight gain. Prior feed restriction had no effect on ability to metabolize diet energy (P > 0.05), although these birds did exhibit increased nitrogen retention compared to birds full-fed from 6 to 11 d. In a second experiment, birds were fed diets with 1.25, 1.38, 1.51, 1.63, 1.76, or 1.88% lysine in the realimentation diet from 12 to 21 d. Lysine level had no effect on growth rate or feed efficiency (P > 0.05) for full-fed birds; however there was a linear (P < 0.05) decline in growth rate from 12 to 21 d in response to extra dietary lysine for the birds previously feed restricted from 6 to 12 d. In a third experiment, birds were fed diets varying in energy (3,000 to 3,300 kcal/kg) or protein (22 to 29% CP) from 12 to 21 d following ad libitum vs 50% feed restriction from 6 to 11 d age. Protein level of the diet had little effect on performance traits to 21 d, although there was an indication of improved growth in response to the higher energy concentration. Birds full-fed from 6 to 11 d showed increased liver size at 21 d when fed more protein, although the converse was true for the restricted birds (P < 0.05). The growth response to diet energy was associated with increased carcass fatness. In general, there does not seem to be any advantage to manipulating diet formulation during realimentation of birds previously nutrient-restricted.

Influence of dietary levels of fat, fiber, and copper sulfate and fat rancidity on cecal activity in the growing turkey

Two experiments were conducted with 6- to 10-wk-old turkeys. In Experiment 1, 6-wk-old turkeys were fed diets varying in level of fat (4.4 to 10%) or fiber (2.5 to 9.0%). The diets also contained extra copper as copper sulfate at either 0.1 or 0.2% of the diet. At 8 wk of age, 15 replicate birds were housed in individual cages and all excreta was collected. Excreta was separated as being "regular" or "cecal" in origin based on appearance. At 10 wk of age, 10 birds per treatment were killed and cecal contents removed under anaerobic conditions. Cecal contents were assayed for various nutrients and viscosity was measured. In a second comparable study, turkeys were fed animal-vegetable fat or regular or rancid canola oil (60.25 vs 120.24 ng/g malonaldehyde, respectively). In Experiment 1, feeding copper sulfate had the most noticeable effect on various cecal parameters. There was an increase (P < 0.01) in dry matter cecal droppings produced and the cecal contents were of increased viscosity (P < 0.05). Copper had no effect on pH or microbial colony count of the cecal contents. Feeding copper resulted in a significant increase in the high molecular weight (> 300,000) fraction of cecal contents and this fraction was of higher viscosity. Feeding copper sulfate resulted in a dramatic increase in copper content of cecal contents (280 to 11,848 ppm), although the copper content of regular excreta was also increased (17 to 1,008 ppm). The various levels of fiber and fat generally had no effect on cecal parameters. Feeding rancid canola oil did result in increased viscosity of cecal contents, compared to the situation seen with fresh canola oil. Fat rancidity per se, however, failed to influence other parameters such as total mass of cecal material produced and composition of cecal material. Feeding copper sulfate or rancid fat will increase the viscosity of cecal material, which may contribute to litter management problems.

Layer performance of four strains of Leghorn pullets subjected to various rearing programs

Two experiments were conducted using four strains of Leghorn pullets, namely Babcock, DeKalb, H & N, and Shaver. Pullets were grown on conventional or low protein diets fortified with additional amino acids. At 18 wk of age, 64 pullets from each strain and diet treatment were transferred to individual laying cages, using eight replicate groups of four adjacently caged birds. In a second experiment, pullets from the four strains were selected based on body weight at 18 wk of age (approximately 1,270 vs 1,650 g). Each weight group and strain was again represented by eight replicate groups of four birds. In Experiment 1, there were no strain or rearing diet effects on egg production (P > 0.05). Rearing diet had little long-term effect on any adult characteristics. There were significant (P < 0.01) strain effects on body weight, feed intake, and egg weight, although these were independent of rearing diet. In Experiment 2, regardless of bird strain, the pullets with smaller body weight matured more slowly (P < 0.01) and produced less total egg mass to 70 wk age (P < 0.05). These smaller birds ate less feed and produced smaller eggs (P < 0.01). There were strain effects, independent of 18-wk body weight, for egg weight and eggshell quality (P < 0.01). It is concluded that minor strain differences exist with respect to response to juvenile nutrition, although such effects are only evident in early lay. All strains of bird remain small, 18-wk body weight is reduced, and these birds subsequently eat less feed and produce smaller eggs.

Effect of dietary fat, fiber, and monensin on cecal activity in turkeys

Two experiments were conducted to determine the physical, chemical, and microbial properties of turkey cecal droppings and relate them to intake of common dietary components, namely fat, fiber, and the anticoccidial, monensin. Experiment 1 involved collection and analysis of physical and chemical properties of cecal and regular droppings from commercial turkey flocks. Experiment 2 tested the effect of dietary fat, fiber, and monensin on growth performance and cecal activity in male turkeys. Compared to regular excreta, cecal droppings analyzed in Experiment 1 were higher in viscosity and fat content, and lower in dry matter, nitrogen, and fiber content (P < 0.05). High dietary fiber and fat significantly (P < 0.05) improved growth performance in Experiment 2. Prolonged feeding of monensin significantly (P < 0.05) reduced cecal evacuation. Results of chemical composition showed that higher dietary fat and fiber significantly (P < 0.01) reduced the fat percentage of cecal contents, whereas prolonged feeding of monensin increased the fat in both cecal contents and droppings. There was no significant effect of any of the treatments on pH, viscosity, and microbial counts of cecal contents. There is the need to identify and characterize the compound responsible for the high viscosity of cecal droppings.