Bacillus subtilis strain specificity affects performance improvement in broilers.

The study reports the effects on broiler performance of a newly isolated Bacillus subtilis strain, which is phylogenetically not closely related to already well-described strains of B. subtilis. In the first experiment, birds were reared in battery cages and exposed to C. perfringens. An increase in growth performance was observed with the strain when compared to the challenged animals. Three additional growth trials were conducted to 35 d of age, in different rearing conditions (genetic breeds, corn-soybean meal-based diet with or without animal proteins, in presence or absence of phytase, on fresh or used litter) to investigate the efficacy and the specificity of this new B. subtilis strain on the improvement of BWG and FCR of broilers in comparison with a B. subtilis-based DFM already used in the field. Whatever the rearing conditions tested, the new B. subtilis strain led to an average 3.2% improvement in feed conversion ratio or bodyweight. Comparatively, the commercial Bacillus strain significantly improved broiler performance in only one trial out of 3 with an average improvement reaching 2%. All these results indicate that this new B. subtilis strain consistently improves broiler performances.

Evaluation of the efficacy of 2-hydroxy-4-methylselenobutanoic acid on growth performance and tissue selenium retention in growing pigs.

The aim of this study was to compare the efficacy of a new organic Se (2-hydroxy-4-methylselenobutanoic acid [HMSeBA]) source (SO) with sodium selenite (SS) and selenized yeast (SY) at various dietary levels for growth performance and tissue Se deposition in growing pigs. A total of 112 crossbred (Pietrain × [Large White × Landrace]) gilts were allotted at an average body weight of 26.73 kg to 7 dietary treatments with 8 replicate pens of 2 pigs per pen. Pigs were fed basal diets unsupplemented or supplemented either with SS, SY, or SO each at 0.1 or 0.3 mg Se/kg of diet for 32 d. Feed intake and BW were recorded during the experimental period. At the end of the experiment, blood, liver, and psoas major muscle of all gilts were collected for total Se and relative bioavailability determination. No differences were observed on final BW, ADG, ADFI, and G:F among dietary treatments. All Se-supplemented groups exhibited greater total Se contents in plasma (P < 0.01) and liver (P < 0.01) compared with unsupplemented control group. However, Se retention in psoas major muscle was improved only when organic Se source (SY or SO) was added to diets (P < 0.01). Regardless the Se level, the Se deposition in muscle was greater (P < 0.01) in pigs supplemented with SO than those supplemented with SY. Slope ratio assay confirmed the greater bioavailability of Se from organic compared with inorganic Se and also revealed that the relative bioavailability of Se from HMSeBA for plasma, liver, and muscle Se response was 170, 141, and 162%, respectively, for SY. This study shows a potential advantage of HMSeBA supplementation in the increase of Se contents in pig tissues, indicating that this new organic Se source could be an alternative source of Se in swine nutrition.

Effect of 2-hydroxy-4-methylselenobutanoic acid as a dietary selenium supplement to improve the selenium concentration of table eggs.

The aim of this study was to compare the effects of a new organic Se [2-hydroxy-4-methylselenobutanoic acid (HMSeBA)] with routinely used mineral and organic Se sources (sodium selenite and selenized yeast) on chosen performance criteria and Se deposition in egg and muscle of laying hens. A total of 240 laying hens (40 wk of age) were randomly assigned to 6 treatments for 56 d with 8 replicates of 5 hens per replicate. The 6 treatments were as follows: control group received basal diet without Se supplementation; the second, fourth, and sixth experimental groups (SS-0.2, SY-0.2, and HMSeBA-0.2, respectively) were fed basal diet supplemented with Se at 0.2 mg/kg from sodium selenite, selenized yeast, and HMSeBA, respectively; and the third and fifth experimental groups (SY-0.1, and HMSeBA-0.1, respectively) were fed basal diet supplemented with Se at 0.1 mg/kg from selenized yeast and HMSeBA, respectively. No difference was observed among dietary treatments on feed intake, egg weight, and laying rate. All hens fed the Se-supplemented diets exhibited greater total Se contents in their eggs compared with control hens (P < 0.01). The egg Se concentrations were greater in hens fed organic Se (HMSeBA-0.2, P < 0.01, and SY-0.2, P < 0.01) than those fed the SS-0.2. In addition, hens fed the diet with HMSeBA-0.2 accumulated more Se in their eggs (+28.78%; P < 0.01) and muscles (+28%; P < 0.01) than those fed the diet supplemented with SY-0.2. These results showed the greater ability of HMSeBA to increase Se deposition in eggs and breast muscle of laying hens, which can subsequently lead to greater supply of Se for humans.

The effect of a non-starch polysaccharide-hydrolysing enzyme (Rovabio® Excel) on feed intake and body condition of sows during lactation and on progeny growth performance.

A total of 200 (Large White × Landrace) sows were used in a 39-day study to evaluate the effects of feeding a non-starch polysaccharide (NSP)-hydrolysing enzyme multicomplex (Rovabio(®) Excel) in conjunction with a high- or reduced nutrient-density diet during lactation on sow body condition, feed intake and progeny performance. Eight sows were selected each week for 25 weeks, blocked by parity and BW into groups of four, and within the block randomly assigned to one of the four treatments (n = 50/treatment). Treatments were: (1) LND: low energy (13.14 MJ of DE/kg), low CP (15%) diet; (2) LND + RE: LND with 50 mg/kg NSP-hydrolysing enzyme; (3) HND: high energy (14.5 MJ of DE/kg), high CP (16.5%) diet; and (4) HND + RE: HND with 50 mg/kg NSP-hydrolysing enzyme. Sows were fed treatment diets from day 109 of gestation until the day of subsequent service. Between weaning and re-service, Rovabio(®) Excel addition to LND diets resulted in an increase in energy intake; however, a reduction was observed when supplemented to the HND diet (P < 0.05). The inclusion of Rovabio(®) Excel increased feed and energy intake during week 3 (days 15 to 21) of lactation (P < 0.05). Sows fed diets supplemented with Rovabio(®) Excel had greater back-fat depth at weaning and service (P < 0.05); however, the magnitude of change in back-fat depth during lactation and from farrowing to service was not different between treatments. Feeding the HND diet increased energy intake before farrowing, throughout lactation and during the weaning to service interval (P < 0.01); however, overall, average daily feed intake tended to be reduced (P < 0.10). At service, sows fed the HND diet were heavier than sows fed the LND diet (P < 0.05); however, the magnitude of change in BW between treatments was not different. Feeding the HND diet to sows resulted in a tendency for heavier piglets at birth (P = 0.10) that tended to grow at a faster rate and be heavier at weaning than piglets from sows fed the LND diet (P = 0.06). These results indicate that NSP-degrading enzymes offer minimal benefit to sows and their progeny when fed before and during lactation; however, increasing energy intake of sows during lactation may beneficially affect progeny.

Wheat-barley-rye- or corn-fed growing pigs respond differently to dietary supplementation with a carbohydrase complex.

Thirty-six pigs (22 kg of BW) were used to evaluate a carbohydrase preparation, with xylanase and ß-glucanase as main activities, added to either wheat-barley-rye- (WBR) or corn-based diets on performance, intestinal environment, and nutrient digestibility. Pigs were offered 1 of 4 different dietary treatments for 27 d according to a factorial arrangement of treatments (a 2 × 2) with 2 cereal types (WBR or corn) and 2 levels of supplemental carbohydrase (0 or 0.01%). Pig growth and feed intake were individually measured every week until the end of the experiment when pigs were slaughtered to obtain samples of digesta and tissues. Cereal type affected performance only during wk 1, in which WBR improved ADG (590 vs. 440 g/d; P = 0.008) and G:F (0.61 vs. 0.43; P = 0.045) compared with corn. The WBR also increased the viscosity of the digestive contents in stomach (1.95 vs. 1.23 mPa·s; P = 0.001) and ileum (6.53 vs. 2.80 mPa·s; P = 0.001) and resulted in greater cecal starch digestibility (95.7 vs. 93.9%; P = 0.012). However, trends for a reduction in digestibility were observed for glucose in the nonstarch polysaccharide (NSP) fraction in the ileum (64.4 vs. 75.8%; P = 0.074) and galactose in the NSP fraction in the cecum (1.4 vs. 1.8%; P = 0.055). The use of the enzyme preparation increased ADFI during wk 2 (1,328 vs. 1,215 g/d; P = 0.028), and increased villus height (423 vs. 390 µm; P = 0.045) and tended to reduce relative pancreas weight (0.16 vs. 0.17% BW; P = 0.079) at d 27. The enzyme also improved cecal starch digestibility (95.5 vs. 94.1%; P = 0.043) and tended to improve ileal energy digestibility (61.3 vs. 53.7%; P = 0.090) and cecal glucose digestibility in the NSP fraction (76.0 vs. 54.5%; P = 0.055). However, it reduced the cecal digestibility of mannose in the NSP fraction (27.0 vs. 50.5%; P = 0.016). Interactions (P < 0.05) between cereal type and enzyme supplementation were observed for ADG and G:F during wk 2, BW and ADG during wk 3, and BW and ADFI over the whole trial; and also for villus-height-to-crypt-depth ratio and for cecal DM digestibility. In all instances, whereas the added enzyme had no effect in the case of the corn diet, improvements were observed with WBR. In conclusion, the multi-enzyme tested had different effects depending on the type of cereal present in the diet.

Effects of dietary supplementation of methionine and its hydroxy analog DL-2-hydroxy-4-methylthiobutanoic acid on growth performance, plasma hormone levels, and the redox status of broiler chickens exposed to high temperatures.

Heat stress is known to impair performance and to induce oxidative stress in poultry. The aim of the present study was to compare the effects of dietary supplementation of dl-methionine (dl-M) or the synthetic analog 2-hydroxy-4-methylthiobutanoic acid (dl-HMTBA) on broiler growth performance, plasma hormone levels, and some oxidative stress-related parameters under conditions of chronic exposure to high temperatures (HT). From 2 to 6 wk of age, male broiler chickens were reared under either a constant temperature of 32°C until 6 wk of age or a normal temperature scheme (gradual decrease to 18°C at 5 wk of age). Chicks in both the normal and HT treatments were provided with a commercial grower diet supplemented with either 1.0 or 1.2 g/kg of dl-M or 1.0 or 1.2 g/kg of dl-HMTBA. Because there were no effects of supplement dose, data were pooled over both doses within each temperature treatment. The chronic HT treatment impaired feed intake and BW gain, but these negative effects were less pronounced when the chickens received dl-HMTBA. Exposure to HT was also associated with decreased (P < 0.001) plasma thyroid hormones and increased (P < 0.0001) plasma corticosterone levels. At 4 wk of age, and irrespective of the supplemental source, chickens subjected to HT were characterized by significantly lower plasma TBA-reactive substance levels. In contrast, at 6 wk of age, plasma TBA-reactive substance levels were significantly increased by HT, but this effect was observed only for the chickens receiving dl-M and not for those receiving dl-HMTBA. High temperatures induced a significant increase in hepatic total glutathione (GSH) and oxidized GSH levels, regardless of the supplemental source. However, the hepatic ratios of reduced GSH to total GSH and reduced GSH to oxidized GSH were highest in chickens supplemented with dl-HMTBA. In conclusion, dl-HMTBA supplementation partially prevented the growth-depressing effects of chronic heat exposure compared with dl-M supplementation. It can be inferred that dl-HMTBA is more efficient in alleviating HT-induced oxidative damage because of a more favorable reduced GSH-to-total GSH ratio.

Ruminococcin C, a new anti-Clostridium perfringens bacteriocin produced in the gut by the commensal bacterium Ruminococcus gnavus E1.

When colonizing the digestive tract of mono-associated rats, Ruminococcus gnavus E1 - a bacterium isolated from human faeces - produced a trypsin-dependent anti-Clostridium perfringens substance collectively named Ruminococcin C (RumC). RumC was isolated from the caecal contents of E1-monocontaminated rats and found to consist of two antimicrobial fractions: a single peptide (RumCsp) of 4235 Da, and a mixture of two other peptides (RumCdp) with distinct molecular masses of 4324 Da and 4456 Da. Both RumCsp and RumCdp were as effective as metronidazole in combating C. perfringens and their activity spectra against different pathogens were established. Even if devoid of synergistic activity, the combination of RumCsp and RumCdp was observed to be much more resistant to acidic pH and high temperature than each fraction tested individually. N-terminal sequence analysis showed that the primary structures of these three peptides shared a high degree of homology, but were clearly distinct from previously reported amino acid sequences. Amino acid composition of the three RumC peptides did not highlight the presence of any Lanthionine residue. However, Edman degradation could not run beyond the 11th amino acid residue. Five genes encoding putative pre-RumC-like peptides were identified in the genome of strain E1, confirming that RumC was a bacteriocin. This is the first time that a bacteriocin produced in vivo by a human commensal bacterium was purified and characterized.

The site of intestinal disappearance of DL-methionine and methionine hydroxy analog differs in pigs.

A study was conducted with pigs to determine the sites of and the influence of dietary wheat middlings (WM) as a fiber source on the absorption of dl-Met (DLM) and dl-2-hydroxy-4-methylthio butanoic acid (HMTBA). Twelve 25-kg barrows were used in a replicated 6 × 4 incomplete Latin-square design with 6 diets and 4 periods per pig. Each pig was surgically fitted with simple T-cannulas in the terminal duodenum and ileum 2 wk before the initiation of the experiment and housed in a stainless-steel metabolism crate. The 6 diets were arranged in a 2 × 3 factorial of WM at 0 (CON) or 8% and Met source including none, DLM, or HMTBA. Supplemental DLM doubled the duodenal free Met concentration from 9.6 to 19.6 g/100 g of DMI. Supplemental DLM also increased the apparent ileal digestibility (AID) of free Met from 52 to 92% (P < 0.05). Adding 8% WM increased (P < 0.01) duodenal NDF concentrations by 2 g/100 g of DMI and decreased (P < 0.05) AID of free Met. No HMTBA was detected in digesta collected from the duodenum or ileum of pigs fed the CON + HMTBA or the WM + HMTBA diets, indicating complete absorption before the terminal duodenum regardless of WM inclusion. Interactions between Met supplementation and WM were observed for the digestibility of all other nutrients (P < 0.05). Fiber and AA digestibility in the ileum were the greatest for the CON + HMTBA diet, and least for the WM + HMTBA diet. The CON + HMTBA diet had greater AID of ADF, NDF, CP, and Thr, and greater AID of ADF, NDF, ash, Arg, Ile, Gly, and Pro when compared with the CON and CON + DLM diets, respectively (P < 0.05). The WM + HMTBA had less AID of ADF, CP, and all AA with the exception of Lys, Trp, and Val when compared with the CON + HMTBA (P < 0.05). In summary, absorption of HMTBA in the pig is complete by the end of the duodenum, but negative interaction between HMTBA and WM can decrease the AID of most AA.

Enzyme complex containing carbohydrases and phytase improves growth performance and bone mineralization of broilers fed reduced nutrient corn-soybean-based diets.

One experiment was conducted to investigate the benefits of a multi-enzyme complex, containing carbohydrases (from Penicillium funiculosum) and phytase (bacterial 6-phytase) activities, on the performance and bone mineralization of broiler chickens fed corn-soybean meal diets. A total of 2,268 male broilers were allocated to 9 treatments, replicated 6 times, in a randomized complete block design from 1 to 43 d. A positive control (PC) diet formulated to be adequate in nutrients and 4 reduced nutrient diets (NC1 to NC4), with gradual decrease on AME, CP, and digestible amino acids (CP-dAA) and available P (avP) and Ca contents, with or without enzyme supplementation, were tested. The nutrient reductions applied were NC1 (-65 kcal/kg, -1.5% CP-dAA) and NC2 (-85 kcal/kg, -3.0% CP-dAA) both with -0.15 percent point avP and -0.12 percent point Ca and NC3 (-65 kcal/kg, -1.5% CP-dAA) and NC4 (-85 kcal/kg, -3.0% CP-dAA) both with -0.20 percent point avP and -0.16 percent point Ca. Supplementation of the NC diets with the enzyme complex increased ADFI (P<0.001), ADG (P<0.001), and reduced feed:gain (P<0.01). The magnitude of the enzyme effect in increasing feed intake and weight gain was greater for the diets with greatest reductions in avP and Ca. Enzyme supplementation increased (P<0.001) feed intake of birds fed on NC diets close to the level of feed consumption of the PC. Enzyme supplementation to NC diets resulted in all cases in lower (P<0.05) feed:gain than the PC. Enzyme supplementation to NC1 and NC3 diets restored bone mineralization to that of the PC, whereas ash and Ca with NC2 and NC4 diets and P with NC4 diet remained lower (P<0.05). These results suggest that the dietary supplementation with a multi-enzyme complex containing nonstarch polysaccharide enzymes and phytase is efficient in reducing the P, energy, protein, and amino acid specifications of corn-soybean meal diets.

Short communication: effects of 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester on milk production and composition of lactating Holstein dairy cows.

Sixteen multiparous Holstein cows were used to determine the effects of 2-hydroxy-4-(methylthio) butanoic acid isopropyl ester (HMBi: 0 vs. 1.26 g/kg of total ration dry matter (DM) and dietary crude protein (CP) concentration [14.7% (low) vs. 16.9% (standard), DM basis] on milk yield and composition using a replicated 4 x 4 Latin square design experiment with 4-wk periods. Cows were fed ad libitum a total mixed ration with a 1:1 forage-to-concentrate ratio (DM basis), and diets provided an estimated 6.71 and 1.86% lysine and methionine, respectively, in metabolizable protein for the low-protein diet and 6.74 and 1.82% in the standard protein diet. Dry matter intake, milk yield, and composition were measured during wk 4 of each period. There were no effects on DM intake, which averaged 24.7 kg/d. There was an interaction between dietary CP and HMBi for milk yield and 3.5% fat-corrected milk (FCM). Feeding HMBi decreased milk and FCM yield when fed with the low-CP diet but did not affect milk or FCM yield when fed with the standard CP diet. Feeding HMBi increased milk protein concentration regardless of diet CP concentration and increased milk protein yield when added to the standard CP diet but not the low-CP diet. The positive effect of HMBi on milk protein yield was only observed at the standard level of dietary CP, suggesting other factors limited the response to HMBi when dietary protein supply was restricted.

Partial Na+ dependence of DL-2-hydroxy-4-(methylthio)butanoic acid uptake in the chicken small intestine.

Methionine hydroxy analogue DL-2-hydroxy-(4-methylthio)butanoic acid (HMTBA) is commonly used as a supplemental source of Met in commercial animal diets. To better understand the uptake of this analogue by the chicken intestine, the aim of the present study was to assess the contribution of Na+ gradient on HMTBA accumulation in everted sacs of the chicken small intestine (duodenum, jejunum, and ileum). In the presence of an H+ gradient, uptake was lower in the absence of Na+ along the chicken small intestine, although no significant differences were detected in the duodenum. In contrast, in the absence of an H+ gradient, no significant differences were detected between the 2 Na+ conditions. In conclusion, the observed relationship between Na+ and H+ dependence indicates the participation of the apical Na+/H+ exchanger in HMTBA uptake in the chicken small intestine.

Conversion of the methionine hydroxy analogue DL-2-hydroxy-(4-methylthio) butanoic acid to sulfur-containing amino acids in the chicken small intestine.

dl-Methionine or its corresponding hydroxy analogue, DL-2-hydroxy-(4-methylthio) butanoic acid (DLHMB), are commonly added to commercial animal diets to satisfy the TSAA requirement. The utilization of DLHMB as a supplementary source of Met begins with its conversion to L-Met via a 2-step mediated process. L-Methionine can then be transsulfurated to L-Cys, which, in turn, can be catabolized to taurine (TAU). In the present study, the capacity of the chicken small intestine to convert DLHMB to L-Met and to use this amino acid as a source for L-Cys and TAU production was evaluated. The appearance of Met in the serosal compartment of everted sacs incubated with DLHMB is higher in the presence of an H(+) gradient (mucosal pH 5.5 vs. 7.4). Serosal Cys and TAU concentration was compared in everted sacs incubated at a mucosal pH of 5.5 with DLHMB or L-Met, and the results show significantly higher values after incubation with the hydroxy analogue. Regional comparisons indicate no significant differences in the appearance of serosal Met and Cys, although lower values were obtained for TAU in the duodenum than in the jejunum and ileum. The profile of non-S amino acids was also determined and revealed no significant differences between DLHMB- and L-Met-incubated sacs. In conclusion, Cys and TAU content in chicken enterocytes is higher when DLHMB is used as a Met source.

Oligomers are not the limiting factor in the absorption of DL-2-hydroxy-4-(methylthio)butanoic acid in the chicken small intestine.

The methionine hydroxy analogue DL-2-hydroxy-4-(methylthio)butanoic acid (HMB) is commonly used as a supplemental source of methionine in commercial animal diets. The HMB free acid is an aqueous solution that contains 88% product in an equilibrium mixture of monomer, dimer, and polymeric compounds. The present study examines whether the presence of these nonmonomeric forms reduces the absorption of the hydroxy analogue in the chicken small intestine. In vivo and in vitro methodologies were used to compare the intestinal absorption of an HMB product containing mainly monomer (HMB-PCM) with commercial HMB. The results from the in vivo perfusion of the jejunum showed no significant differences between the 2 hydroxy analogue sources in monomer absorption from the intestinal lumen, tissue accumulation, or plasma concentration. The results also indicate that the nonmonomeric forms are hydrolyzed during perfusion. Moreover, monomer tissue accumulation in everted sacs showed no significant differences between substrates, either in the presence or in the absence of a H+-gradient; a higher value was observed in the jejunum and ileum in comparison with the duodenum. Similarly, serosal appearance in H+-gradient conditions did not differ significantly between substrates, and it showed the same regional profile as in tissue accumulation. Oligomer hydrolysis was confirmed in vitro without significant differences between segments. In conclusion, the presence of nonmonomeric forms is not a limiting factor in HMB absorption, apparently because of the hydrolytic capacity of intestinal mucosa, as confirmed by experiments in vivo and in vitro.

Performance of pureline broiler breeders fed two levels of vitamin E.

Reported in this paper is an experiment designed to evaluate responses of two commercial broiler dam purelines (A and B) continuously fed 10 or 300 IU of vitamin E/kg from 168 to 441 d of age. Prior to Day 168, all pullets were fed diets containing 10 IU of vitamin E/kg. During the early laying period, percentage hen-day ovulations and percentage hen-day normal egg production were similar for both lines and diets. During the latter part of the laying cycle, there were differences between lines for these traits (A > B), as well as for BW and egg weight for which line differences were reversed (A < B). Also during this period, percentage hen-day ovulations and percentage hen-day normal egg production differed between diets (300 > 10 IU/kg). These differences between diets were consistent with the greater number of females that entered lay and higher hen-housed egg production of the 300- than 10-IU/kg group. Although during the laying cycle all females received a fixed amount of feed, BW gains were greater for Line B than A and for the 300- than the 10-IU/kg level of vitamin E. Heterophil (H):lymphocyte (L) ratios, percentage livability, and relative asymmetries of shank length and diameter were similar among groups. Pullets from Line B and those fed the higher level of vitamin E exhibited more fear than their counterparts. Head shaking did not differ between vitamin E levels; however, there was a line-by-time of day interaction for this behavior. The 30-fold difference in dietary vitamin E was reflected by a 15-fold difference in plasma vitamin E levels in both lines. For vitamin E level in the yolk, however, there was a line-by-diet interaction. The interaction resulted from no difference between lines at the 10 IU/kg level and differences of 10- and 6+-fold in Lines B and A at the 300 IU/ kg level, respectively. Overall, responses to continuous feeding of vitamin E at these levels were influenced by genetic stock, age, duration of feeding, and measurement criteria.

Antibody responses of hens fed vitamin E and passively acquired antibodies of their chicks.

Antibody responses of hens and their progeny were studied in commercial broiler nuclear lines. Starting at 168 days of age, individually housed pullets from lines A and B were fed a 16% crude protein and 2752 kcal metabolizable energy/kg mash diet supplemented with either 10 or 300 IU/kg of vitamin E fed as dl-alpha-tocopherol acetate. Fifty-eight days later (226 days of age), 12 hens per line-vitamin E subclass were inoculated i.v. with 0.1 ml of a 2.5% suspension of sheep red blood cells (SRBC). Plasma antibody titers were measured 6, 20, 40, 54, 70, and 88 days after inoculation. Hens from both lines were artificially mated to males from line C, and progeny from eggs collected 9-15, 25-30, and 65-70 days after inoculation were tested for antibodies to SRBC. Hens were reinoculated i.v. with 0.1 ml of 0.25% SRBC 88 days after the first inoculation, and their antibody levels were measured 3, 6, and 20 days later. Eggs laid 10-13 days after reinoculation were incubated, and antibody titers of chicks were measured at hatch. Antibody response of hens to an initial inoculation of SRBC was line-diet-time after inoculation specific. In line A, titers were greater for hens fed the lower than the higher vitamin E diet, whereas diet had no effect on the antibody levels in line B. Line effects (A > B) were observed on days 6 and 20 after inoculation but not thereafter. After the second inoculation, dietary vitamin E level had no effect on antibody levels of hens within lines, whereas a between-line difference (A > B) was observed for the lower but not the higher level of dietary vitamin E. Although there was no difference between diets for antibody transferred to progeny by line B, there was a difference (lower > higher) for line A. After reinoculation of their dams, antibody titers of chicks from line A, but not line B, reached levels similar to those after the first inoculation. Antibody levels were higher for chicks at hatch than in 16-day embryos or 10 days posthatch. The results of this research suggest genetic variation in response to immune stimulation by dietary vitamin E.

Glucose-insulin relationships and thyroid status of cockerels selected for high or low residual food consumption.

The plasma glucose-insulin relationships and thyroid status were investigated in two lines of adult cockerels divergently selected for high (R+) or low (R-) residual food consumption (RFC). For a given body weight, R+ birds had a 74% higher food intake than R- birds. Plasma glucose concentrations were significantly lower in the R+ line compared with the R- when fasted, whereas R+ birds exhibited a significantly lower plasma insulin concentration than R- birds either in fed or fasted state. After an overnight fast, R+ birds also exhibited a higher sensitivity to exogenous insulin in view of its more pronounced hypoglycaemic effect. After an oral glucose load, the glucose disposal of R+ cockerels was faster despite lower glucose-induced plasma insulin concentration. Whilst plasma triacylglycerol concentrations were lower in the R+ line when fed, plasma non-esterified fatty acid concentrations were higher in fasted R+ than R- cockerels (684 v. 522 mumol/l). Higher plasma triiodothyronine concentrations were observed in fed R+ compared with R- birds (3.0 v. 2.1 nmol/l respectively). The higher plasma concentrations of triiodothyronine associated with lower concentrations of insulin could account for the leanness and the elevated diet-induced thermogenesis previously observed in the R+ line.

Immune competence of chicks from two lines divergently selected for antibody response to sheep red blood cells as affected by supplemental vitamin E.

Effects of dietary vitamin E on responses to SRBC antigens and Escherichia coli infection were studied in chicks from White Leghorn lines selected for 24 generations for high (HAS) and low (LAS) antibody responses to SRBC. Chicks were fed corn-soybean diets consisting of either high (300 IU per kg feed) or low (10 IU per kg feed) concentrations of vitamin E from the day of hatch through the end of experiment. The LAS chicks were heavier than the HAS chicks at 14 d of age and thereafter; there was no difference in BW between vitamin E concentrations. At 37 d of age, chicks were inoculated via the brachial vein with 0.1 mL of 0.25% SRBC suspension. Antibody titers at 6 and 10 d after inoculation were higher in HAS than in LAS chicks. At 6 and 10 d after inoculation with SRBC, antibody responses were lower in LAS chicks fed the diet containing the higher vitamin E concentration than in those fed the diet containing the lower concentration of vitamin E. At 64 d of age, chicks were injected in the posterior thoracic air sac with 0.1 mL of 10(-2) or 10(-4) dilution of Escherichia coli and scored for pericardial and air sac lesions. The HAS chicks were more susceptible to E. coli infection than LAS chicks as measured by lesion scores and BW changes. Although dietary vitamin E had no effect on lesion scores in either line, BW loss at 24 h after E. coli inoculation was significantly reduced in HAS chicks fed the higher concentration of vitamin E. The dosage of E. coli had no effect on lesion scores and BW changes. These results suggest that genetic selection might have changed immune competence in relation to responses to dietary vitamin E, and the optimum dietary concentration of vitamin E depends on genotype, among other factors.

Vitamin E and immune responses of broiler pureline chickens.

Immunological responses of cockerels fed diets containing either 10 or 300 mg/kg of vitamin E were measured in three commercial broiler nuclear lines designated as A, B, and C. All cockerels were fed the 10 mg/kg diet to 91 d of age, at which time half were continued on that diet and the other half were fed a diet supplemented to contain 300 mg/kg of vitamin E. Sixteen days after feeding the diets, cutaneous basophil hypersensitivity (CBH), which is an in vivo, cell-mediated immune response, was determined as the increase in toe-web skin thickness 24 h after an injection with phytohemagglutinin-P (PHA-P). Twenty-two days after feeding the diets, heterophils and lymphocytes were enumerated. At this time cockerels were also inoculated intravenously with 0.1 mL of 0.25% SRBC. The injection with SRBC was repeated 27 d later. Six and 20 d after each injection, antibody titers were determined. Mercaptoethanol-resistant (IgG) and mercaptoethanol-sensitive (IgM) antibodies were also measured in the secondary titers. The ratio of heterophils to lymphocytes increased, and CBH response was depressed by feeding the higher vitamin E diet. For cockerels of Lines A and B, the higher level of vitamin E maintained primary and secondary SRBC antibody levels, whereas for Line C, levels were depressed. The effect of the higher vitamin E diet on IgG and IgM was also stock-dependent. The enhanced heterophil:lymphocyte ratio from feeding vitamin E suggests an improved phagocytic ability of the immune system. Relative asymmetries for toe-web skin thickness and shank length were similar for the three lines.

Effects of chronic heat exposure and protein intake on growth performance, nitrogen retention and muscle development in broiler chickens.

The respective effects of ambient temperature, dietary crude protein and feed intake were investigated in finishing chickens and the consequence of protein supplementation under high temperature conditions was analysed in particular. Heat-related reduction in growth was associated with decreased nitrogen retention (-30 or -35% according to the diet), which could not be explained by the observed lower feed intake alone. Tissue samples performed in 5- to 6-week-old chicks showed varying effects of heat according to the muscles studied: at 32 degrees C, the proportion of Pectoralis major muscle (in percentage of body weight) appeared slightly reduced (reduction lower than 10%), whereas the proportion of two leg muscles were increased (+10 to +15% for the Sartorius muscle; +5% for the gastrocnemius muscle). At 32 degrees C, providing a high protein diet significantly (P < 0.05) increased weight gain and feed efficiency, and slightly improved whole body protein deposition.

Genetic parameters of body weight of broiler chickens measured at 22 degrees C or 32 degrees C.

1. Male broilers (n = 1521) from 247 families were reared from 4 to 6 weeks of age at 22 degrees or 32 degrees C. 2. Genetic correlations between measurements recorded at 22 degrees C and 32 degrees C were 0.73 +/- 0.12 for weight gain between 4 and 6 weeks and 0.74 +/- 0.08 for food conversion ratio (FCR). Genes controlling weight gain at both temperatures differed to some extent. 3. Heritability of weight gain from 4 to 6 weeks was much lower at 32 degrees C than at 22 degrees C (0.13 +/- 0.03 vs 0.24 +/- 0.04): selection for increased body weight will thus be much less efficient at 32 degrees C than at 22 degrees C. 4. Conversely, heritabilities of the FCR were very similar at the 2 temperatures (0.28 +/- 0.04 at 22 degrees C and 0.27 +/- 0.04 at 32 degrees C). Selecting for FCR would thus be efficient at 32 degrees C too. 5. These results justify, at least under our experimental conditions, selecting broiler lines for improved growth performance at 22 degrees C. However, it could be more efficient if broilers are to be reared in hot climates to select for improved FCR rather than for increased body weight.