Effects of caponization and different forms of exogenous androgen implantation on immunity in male chicks.

This study determined the caponization effects on the immune responses in male chicks. Different forms of exogenous androgen implantation on male chick immunity were compared. Healthy, uniform male Single Comb White Leghorn chicks were caponized at 3 wk of age. Birds were housed in individual cages (35 x 30 x 40 cm, length x width x height). Each of 27 sham-operated (sham) and caponized (capon) male chickens were used for trial 1. Trial 2 used 60 capons divided into 4 treatments with implants of either 1 mm i.d. x 3 mm o.d. 58 mg of cholesterol, testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT). The exogenous androgen was implanted immediately after caponization and resupplied every 4 wk for an entire 13-wk feeding trial. The results from trial 1 showed that the relative bursa weight increased compared with the sham treatment (P < 0.05). The 2 wk post-Newcastle disease virus titer and the delayed-type hypersensitivity (DTH) of 48 h post-phytohemagglutinin phosphate (PHA-P) injection were increased compared with the sham treatment (P < 0.05). In trial 2, implanted 5alpha-DHT and 19-NorT could decrease the relative bursa weight in capons (P < 0.05). The 2 wk post-Newcastle disease virus titer in the 5alpha-DHT group was higher than that in the cholesterol group (P < 0.05). The 19-NorT group had the highest (P < 0.05) PHA-P response. Peripheral blood lymphocyte subset population analysis revealed that the percentage of CD4 T cells in the TES group was lower (P < 0.05) compared with that of the 5alpha-DHT group. Differently, the percentage of CD8 T cells in the TES and 19-NorT groups was higher (P < 0.05) than that in the 5alpha-DHT group. Male chicks that were caponized had increased bursa weight and PHA-P response, whereas different forms of exogenous androgen implantation reverted the phenomena in an order of potency of 5alpha-DHT and 19-NorT > TES, and the PHA-P response was TES > 5alpha-DHT >19-NorT.

Effect of caponization and exogenous androgens implantation on blood lipid and lipoprotein profile in male chickens.

This study investigated effects of caponization and different forms of androgen implantation on blood lipid and lipoprotein profile of capons to understand the role of different androgens. Male chickens were caponized at 12 wk of age and selected at 16 wk of age for a 10-wk feeding period. Sixteen intact caponized (capon) male chickens and 16 female chickens were assigned for trial 1, and 16 sham-operated (sham) male chickens and 64 capons were selected for trial 2, in which capons were randomly divided into cholesterol (CHOL), testosterone (TES), 5alpha-dihydrotestosterone, or 19-nortestosterone (19-NorT) implantation at 16, 20, and 24 wk of age. Trial 1 showed that caponization decreased TES concentration (P < 0.05) in male chickens while showing no difference with females (P > 0.05). Caponization increased lipoprotein lipase (LPL) activity and relative abdominal fat weight (P < 0.05) to a level compatible with females (P > 0.05). Caponization also increased low-density lipoprotein (LDL) content and LDL-protein percentage (P < 0.05) but decreased high-density lipoprotein-free CHOL percentage (P < 0.05) compared with intact males. In trial 2, androgen implantation showed lower relative abdominal fat weight (P < 0.05) than CHOL. Only 19-NorT reached a level compatible with the sham (P > 0.05). Cholesterol implantation increased LPL activity compared with the sham (P < 0.05), and 19-NorT and 5alpha-dihydrotestosterone showed the lowest LPL activity (P < 0.05). Different androgen implantations increased LDL and very low density lipoprotein + LDL ratios and decreased high-density lipoprotein ratio (P < 0.05) to the compatible level with the sham (P > 0.05). Different levels of androgen implantation also demonstrated changes in LDL triacylglyceride and protein percentage and reached a level compatible with the sham (P > 0.05). Caponization decreased blood TES concentration in male chickens, increased LPL activity, and changed the lipoprotein composition, leading to an increase in abdominal fat weight. Results of different androgen implantations in capons demonstrated no difference in lipoprotein profile between androgens, but 19-NorT performed most effectively in abdominal fat accumulation recovery.

Effects of caponization and testosterone implantation on immunity in male chickens.

This study examined the effects of caponization using different doses of testosterone (TES) on sexuality, hematology, and immune responses in male chickens. Healthy male chickens were caponized at 12 wk of age and selected at 16 wk of age for a 10-wk experiment. Fifteen intact male and 15 caponized male chickens were assigned to trial 1. In trial 2, ten sham-operated male chickens (sham) and 40 capons (randomly divided into 4 treatments) were implanted with cholesterol (CHOL, 9.24+/-0.36 mg), low TES (5.88+/-0.23 mg), medium TES (9.81+/-0.17 mg), or high TES (16.7+/-0.24 mg) administered at 16, 20, and 24 wk of age. Results from trial 1 showed caponization decreased the comb length, height and weight, and hematocrit (P<0.05) and increased the hemagglutination inhibition (HI; 1 wk postchallenge) and hemagglutination titer after Newcastle disease virus (NDV) and SRBC injections (P<0.05). In trial 2, the medium TES increased the comb length and height as compared with the CHOL group. Only the high TES increased the comb weight (P<0.05). The HI titer (1 wk postchallenge) in the CHOL group was higher than the sham (P<0.05). The medium TES decreased the HI titer (P<0.05) to the level of the sham (P>0.05). The phytohemagglutinin response was higher in the high TES group 24 h postinjection (P<0.05) and in the medium TES 48 h postinjection (P<0.05) as compared with the CHOL group. High dose TES implantation decreased the white blood cell counts as compared with the CHOL and sham groups (P<0.05). It appears that caponization decreased the blood androgen concentration and enhanced the humoral (anti-NDV and anti-SRBC) immune response. Testosterone implantation up to a threshold concentration could inhibit the humoral (anti-NDV) immune response and increase the cell-mediated (phytohemagglutinin) immune response.

Effect of caponization and different exogenous androgen on hepatic lipid and beta-oxidase of male chickens.

Caponization and different exogenous androgens effects hepatic lipid and beta-oxidation metabolism in male chickens compared with intact male and female. Healthy male chickens were caponized at 12 wk old and selected at 16 wk of age for a 10-wk feeding-trial. Sixteen each male caponized (capon) and female chickens were assigned for trial 1, and 16 sham-operated (sham) and 64 capons were selected in trial 2, in which capons were randomly divided into 4 treatments and implanted (1.62 mm i.d. x 3.16 mm o.d., 10.4 +/- 0.4 mg) with cholesterol (CHOL), testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT) at 16, 20, and 24 wk of age. In trial 1, caponization increased abdominal fat weight, hepatic total lipid content, and saturated fatty acid percentage more than males (P < 0.05), and the last achieved compatible level to females (P > 0.05). Caponization increased NAD phosphate-malate dehydrogenase (MDH) activity more than males, but was still lower than females (P < 0.05). Capons showed lower enoyl-coenzyme A hydratase (ECH) and 3-ketoacyl-coenzyme A thiolase (KT) activities than males (P < 0.05) and lower acyl-coenzyme A dehydrogenase activity than females (P < 0.05). In trial 2, the CHOL group increased abdominal fat weight and total hepatic lipid content more than the sham (P < 0.05), and different forms of TES groups appeared to have lower abdominal fat weight (P < 0.05), but only the 19-NorT group achieved a compatible level to the sham (P > 0.05). Cholesterol or different forms of TES implantation increased hepatic MDH activity more than the sham (P < 0.05). Cholesterol implantation decreased ECH and KT activities more than the sham, but the 5alpha-DHT or 19-NorT group showed a compatible ECH activity to the sham (P > 0.05). The 19-NorT group also increased KT activity, but was still less than the sham (P > 0.05). Capons increased abdominal fat weight and hepatic lipid biosynthesis more than males, mainly because capons raised MDH activity and reduced ECH and KT activities. Different forms of TES-implanted capons decreased abdominal fat weight, and hepatic lipid biosynthesis order was 19-NorT, 5alpha-DHT, and TES.

Effect of caponization and testosterone implantation on hepatic lipids and lipogenic enzymes in male chickens.

This study was conducted to determine the role and effects of testosterone in lipogenesis by measuring and analyzing the lipid composition and lipogenic enzyme activity of livers from capons treated with various doses of exogenous testosterone implant. Healthy and uniform male Single Comb White Leghorn chickens were caponized at 12 wk of age. Sixteen-week-old capons were randomly selected for a 10-wk experiment. Fifteen intact males and 15 capons were used for trial 1. In trial 2, 10 sham-operated males and 40 capons were used. The capons were randomly divided into 4 independent treatments with sialistic implants of cholesterol (1.62 mm i.d., 3.6 mm o.d., 9.24 +/- 0.36 mg; CHOL), low testosterone (1 mm i.d., 3 mm o.d., 5.88 +/- 0.23 mg), medium testosterone (1.62 mm i.d., 3.16 mm o.d., 9.81 +/- 0.17 mg), or high testosterone (2 mm i.d., 4 mm o.d., 16.7 +/- 0.24 mg). In trial 1, the results showed that caponization increased total hepatic lipid and triacylglycerol contents and decreased the nonesterified fatty acid content (P < 0.05) compared with the intact male. Meanwhile, caponization increased nicotinamide adenine dinucleotide phosphate -malic dehydrogenase (MDH) activity and MDH mRNA content (P = 0.09) simultaneously. In trial 2, comparing treatments with the various implantation doses of testosterone, the liver triacylglycerol content of capons the medium-dose implantation was decreased as compared with those receiving CHOL (P < 0.05). The total lipid and phospholipid contents of liver were decreased in capons receiving the high-dose implantation (P < 0.05), whereas the relative weight and nonesterified fatty acid content were increased (P < 0.05) and reached the same level as those in the sham treatment (P > 0.05). With an increased implantation dose, MDH activity of capons receiving the medium dose or higher was not different from those receiving the CHOL and sham treatments (P > 0.05). The increase in MDH activity at the transcriptional and translational levels suggests that caponization may positively regulate hepatic lipogenesis. In contract, implantation of testosterone up to the threshold concentration depressed hepatic lipogensis and lipid accumulation.

Effects of caponization and different exogenous androgen on the bone characteristics of male chickens.

The effects of caponization and androgen implantation on the bone characteristics of male chickens were evaluated. Healthy Single Comb White Leghorn cockerels were caponized or sham operated (sham) at 12 wk old. Sixteen birds from each group were selected for a 14-wk experiment in trial 1. Sixteen birds from the sham group and 64 from the caponized group (randomly allocated into 4 treatments) were implanted with 10.4 +/- 0.4 mg (1.62-mm i.d., 3.6-mm o.d.) of cholesterol, testosterone (TES), 5alpha-dihydrotestosterone (5alpha-DHT), or 19-nortestosterone (19-NorT) and were assigned to trial 2 for a 14-wk experiment. The results from trial 1 showed that caponization increased BW (P < 0.05) and decreased tibia stress, ash content, and P content with higher blood P concentration (P < 0.05) as compared with the sham group. In trial 2, the cholesterol implantation group showed the lowest tibia breaking strength, bending moment, stress, and ash content (P < 0.05). The 19-NorT implantation group showed decreased (P < 0.05) blood Ca and P concentration but increased tibia ash and P content, reaching the same level as the sham group (P > 0.05). The adverse effects of caponization on bone characteristics could be improved using androgen implantation. Among the implantation groups, the 19-NorT implantation group showed the best improvement in tibia breaking strength and bending moment, followed by the TES and 5alpha-DHT groups. The TES group showed the best improvement in tibia stress, followed by the 19-NorT and 5alpha-DHT groups.

Caponization and testosterone implantation effects on blood lipid and lipoprotein profile in male chickens.

To understand the role of lipid metabolism in increasing body fat accumulation after caponization of male chickens, trials were conducted to determine the effects of levels of testosterone implantation on lipoprotein composition. Male chickens were caponized at 12 wk and selected at 16 wk for a 10-wk feeding experiment. Fifteen male and 15 caponized (capon) chickens were used in trial 1. Ten sham operated chickens (sham) and 40 capons were randomly divided among 4 treatments in trial 2; the treatments were as follows: implantation of cholesterol (1.62 mm i.d. x 3.16 mm o.d., 9.24+/-0.36 mg) or implantation of testosterone at low (1 mm i.d. x 3 mm, o.d., 5.88+/-0.23 mg), medium (1.62 mm i.d. x 3.16 mm, o.d., 9.81+/-0.17 mg), or high (2 mm i.d. x 4 mm, o.d., 16.7+/-0.24 mg) dose. The results of trial 1 showed that caponization decreased (P < 0.05) blood testosterone concentrations and increased (P < 0.05) abdominal fat weight and relative abdominal fat weight in capons. Caponization also increased low density lipoprotein (LDL), high density lipoprotein (HDL), LDL protein, and HDL protein and decreased LDL-free cholesterol (LDL-FC), HDL-FC, and HDL-phospholipid (HDL-PL) percentages (P < 0.05). In trial 2 capons implanted with increasing testosterone levels exhibited proportional increases in blood testosterone concentration, although blood testosterone concentration in implanted capons were not fully restored to those of the sham group. High dose testosterone implantation inhibited abdominal fat accumulation and increased glucose and glycerol concentrations compared with the cholesterol implantation. Caponization of male chickens decreased the androgen level and increased the blood triacylglyceride content. Caponization also changed the lipoprotein profiles, which resulted in increased lipid storage capacity. The testosterone concentration, therefore, must achieve threshold concentrations to inhibit lipid accumulation in the testosterone implanted capon.

Effects of sources of protein and enzyme supplementation on protein digestibility and chyme characteristics in broilers.

1. The purpose of this study was to evaluate the effects of protein source and enzyme supplementation on protein digestibility and chyme characteristics in broilers. 2. One hundred and twenty growing (13 d old) and 60 finishing (34 d old) Arbor Acre strain commercial male broilers were selected and placed into individual metabolic cages. 3. The experiment was a 5 x 2 factorial arrangement with 5 different sources of protein: casein, fish meal, soybean meal (SBM), soy protein concentrate (SPC), maize gluten meal (MGM) and two levels of protease (bromelain), 0 and 65 CDU/kg diets. 4. The diets were iso-nitrogenous and semi-purified, with Cr2O3 as an indicator for determination of ileal digestibility and chyme characteristics. 5. Apparent ileal protein digestibility (AIPD) in both growing and finishing chickens was highest on the casein diet, followed by fish meal, SBM, SPC and MGM. 6. Enzyme inclusion did not improve protein digestibility, but significantly decreased the digesta pH value in the gizzard and increased pH in the ileum in the 3-week-old broilers. 7. The digesta pH values in the gizzard and duodenum were significantly lower in the SBM and fish meal groups compared with the other protein groups. The molecular weight distribution pattern of the soluble protein in the chyme of the gastrointestinal (GI) segments showed a similar trend, regardless of the enzyme inclusion or the stage of growth. 8. The molecular weight profile of soluble protein changed dynamically in the casein fed broilers from the gizzard to ileum and the low molecular weight proteins, < 7 kDa, reached maximum levels at the ileum. The molecular weight profile of the soluble protein in the SBM and SPC changed between the jejunum and the ileum and in the intermediate molecular soluble protein weight (7 to 10 kDa) was significantly decreased. This indicated that the hydrolysis process began from the middle to the posterior end of the small intestine. 9. Similar profiles were also shown with fish meal protein. The pattern of distribution, however, did not show any prominent change in the GI segments of the MGM group. 10. The pepsin, trypsin and chymotrypsin protease activity in the gizzard and duodenum were highest in the casein group and lowest in the MGM group as compared with the other protein groups. 11. The rate change in the patterns of molecular weight distribution in soluble protein and the digestive enzyme activity provide indications of the partial digestibility of different protein sources. The exogenous enzyme, bromelain, did not show any beneficial effect on protein digestion.