Unsupplemented Birds Research Articles

Live Performance and Microbial Load Modulation of Broilers Fed a Direct-Fed Microbials (DFM) and Xylanase Combination.

The animal industry, which focuses on producing protein for human consumption, is continuously seeking solutions that can enhance both animal performance and health at a low cost. Several feed additives are currently being used to improve the nutritive value of feed as well as replacing the subtherapeutic levels of antibiotic growth promoters (AGP). This study was designed to investigate the effect of a feed additive that is a blend of multi-strain Bacillus spp. probiotics and a xylanase in a 2 × 2 factorial dietary treatments design, testing two levels of the feed additive blend (0 and 100 g/MT) and two cereal grain types (corn and wheat) on live performance, gut lesions, environmental Clostridium perfringens load, and pathogen load in the digesta of broiler chickens (E. tenella, total aerobic count cells (APC), E. coli, and C. perfringens). Day-old chicks were randomly placed in 10 replicate pens per treatment with 52 birds per replicate and grown to 42 d of age. Data were analyzed by two-way ANOVA. At 42 d, birds fed EnzaPro were heavier (p < 0.0004) than unsupplemented birds. An improvement in FCR (p = 0.03) was observed from 1 to 42 d by approximately two points in both corn- and wheat-based diets supplemented with EnzaPro. In wheat-based diets, supplementing EnzaPro reduced (p < 0.0001) a 21 d lesion score of intestines with a further reduction (p < 0.02) at 42 d. EnzaPro reduced (p < 0.03) litter moisture by approximately 1% compared to non-supplemented EnzaPro in both corn- and wheat-based diets. Pathogen load in digesta (C. perfringens, E. tenella, APC, and E. coli) was reduced (p < 0.0002) when EnzaPro was supplemented in diets. It can be concluded that EnzaPro (a blend of DFM Bacillus spp (1 × 105 CFU/g feed) and xylanase (10 XU/g feed)) may be used in both corn- and wheat-based diets to improve the performance and gut health of broilers.

Effect of rice distillers dried grains with solubles and rice gluten meal along with enzyme supplementation on the growth performance, nutrient utilization, production efficiency, and cost economics of broiler chicken production

An experiment was conducted to evaluate the effect of feeding rice distillers dried grains with solubles (rDDGS) and rice gluten meal (RGM) combination with enzyme supplementation on the production performance of broiler chickens. The experimental diets consisted of the following: T1 (no rDDGS/RGM/enzyme), T2 (no rDDGS/RGM, multienzyme), T3 (12.5% rDDGS, 15.0% RGM, no enzyme), T4 (12.5% rDDGS, 15.0% RGM, protease enzyme), T5 (10.0% rDDGS, 12.5% RGM, no enzyme), and T6 (10.0% rDDGS, 12.5% RGM, protease enzyme). Each treatment was assigned 6 replicate groups of birds randomly with 8 birds in each group (48 birds/ treatment). The results revealed the poor growth performance, nutrient utilization, and production efficiency of birds fed a combination of 12.5% rDDGS and 15.0% RGM, followed by the combination of 10.0% rDDGS and 12.5% RGM compared to birds fed no rDDGS and RGM. Enzyme supplementation resulted in significantly (P < 0.01) better growth performance, nutrient utilization, and production efficiency of the birds compared to unsupplemented birds. It was concluded that inclusion of a combination of 10.0% rDDGS and 12.5% RGM as a replacement for soybean, along with dietary enzyme supplementation, can be a potential nutritional strategy for economic broiler chicken production.

Food supplementation affects gut microbiota and immunological resistance to parasites in a wild bird species

Abstract Supplemental feeding can increase the overall health of animals but also can have varying consequences for animals dealing with parasites. Furthermore, the mechanism mediating the effect of food supplementation on host–parasite interactions remains poorly understood. The goal of the study was to determine the effect of food supplementation on host defences against parasitic nest flies and whether host gut microbiota, which can affect immunity, potentially mediates these relationships. In a fully crossed design, I experimentally manipulated the abundance of parasitic nest flies Protocalliphora sialia and food availability then characterized the gut microbiota, immune responses and nest parasite abundance of nestling eastern bluebirds Sialia sialis. Food supplemented birds had 75% fewer parasites than unsupplemented birds. Parasite abundance decreased throughout the breeding season for unsupplemented birds, but abundance did not change throughout the season for supplemented birds. Food supplementation increased overall fledging success. Parasitism had a sublethal effect on blood loss, but food supplementation mitigated these effects by increasing parasite resistance via the nestling IgY antibody response. Food supplementation increased the gut bacterial diversity in nestlings, which was negatively related to parasite abundance. Food supplementation also increased the relative abundance of Clostridium spp. in nestlings, which was positively related to their antibody response and negatively related to parasite abundance. Synthesis and applications. Overall, the results of this study suggest that food supplementation, especially early in the breeding season, increases resistance to parasitism during the early life stage of the host, which might be mediated by the gut microbiota. Wildlife food supplementation is a common pastime for humans worldwide and therefore it is important to understand the consequences of this activity on animal health. Furthermore, supplemental feeding could induce resistance to detrimental parasites (e.g. invasive parasites) in hosts when management of the parasite is not immediately possible.

Red coloration varies with dietary carotenoid access and nutritional condition in kittiwakes.

Carotenoid-based ornaments are common signaling features in animals. Although the mechanisms that link color-based signals to individual condition is key to understanding the evolution and function of these ornaments, they are most often poorly known. Several hypotheses have been posited. They include: (i) the role of foraging abilities on carotenoid acquisition and thereby carotenoid-based ornaments, and (ii) the role of internal processes linked to individual quality on the allocation and conversion of carotenoids in integuments. Here, we tested the influence of dietary carotenoid access versus internal process on gape coloration in black-legged kittiwakes (Rissa tridactyla). This seabird displays a vibrant red gape, whose coloration varies with individual quality in males and is due to the deposition of red ketocarotenoids, such as astaxanthin. We decreased hydroxycarotenoid and ketocarotenoid levels in plasma, but increased efficiency in internal processes linked to nutritional condition, by supplementing breeding males with capelin, a natural energy-rich fish prey. We found that, despite having lower carotenoid levels in plasma, supplemented birds developed redder coloration than control birds, but only in the year when dietary levels of astaxanthin in the natural diet were low. In contrast, in the astaxanthin-rich year, supplemented males had a less-red gape than unsupplemented birds. These results suggest that inter-individual differences in internal processes may be sufficient to maintain the honesty of gape coloration under conditions of low dietary astaxanthin levels. Nonetheless, when inter-individual variations in dietary astaxanthin levels are elevated (such as in the crustacean-rich year), carotenoid access seems a more limiting factor to the expression of gape coloration than internal processes. Therefore, our study revealed a complex mechanism of gape color production in kittiwakes, and suggests that the main factor maintaining the condition dependency of this ornaments may vary with environmental conditions and diet composition.

Supplementation of Protected Sodium Butyrate Alone or in Combination With Essential Oils Modulated the Cecal Microbiota of Broiler Chickens Challenged With Coccidia and Clostridium perfringens

The objective of this study was to determine the effects of protected sodium butyrate (SB), and protected sodium butyrate plus essential oils (carvacrol and ginger; SBEO) on the cecal microbiota of broilers challenged with Eimeria maxima and Clostridium perfringens. Birds were assigned to 4 treatments (8 replicates pens of 58 birds/pen): unchallenged control; challenged control; challenged and supplemented with SB; challenged and supplemented with SBEO. On d 13, challenged birds were orally inoculated with ~5,000 Eimeria maxima oocysts. On d 18-19, the same birds were exposed to Clostridium perfringens via drinking water (~ 8 log CFU/ml). Cecal excreta was collected at d 12, 18, 21, and 28 for microbiome analysis through 16s rRNA sequencing using Illumina MiSeq platform and analyzed using QIIME v. 1.9.1 The cecal microbiota was analyzed over time within each experimental group. The inclusion of SB alone or in combination with EO contributed to larger variations in the cecal microbiota over time than the unsupplemented treatments, as shown by the diversity indices. The community structure and abundance of the cecal microbiota were significantly different across ages, especially in the groups supplemented with SB and SBEO. As shown in the PCoA analysis, the supplementation of SB led to a more stable microbial community and lower between-sample variability over time. In the unchallenged control birds, Ruminococcus decreased (p = 0.006), whereas Bacteroides and Clostridiales increased (p ≤ 0.02) as the birds aged. In the challenged control group, however, the frequency of Coprococcus and Blautia decreased as birds aged (p ≤ 0.01), and, Clostridiales did not increase. Supplementation of SB, but not SBEO, increased the frequency of Lactobacillus (p = 0.01) on d 12 compared to d 18 and d 28, and prevented the reduction in the frequency of Blautia as the birds aged. Nevertheless, supplementation of SB and SBEO contributed to unique changes in the predicted functions of the cecal microbiota over time, which was not observed in the unsupplemented birds. SB and SBEO modulated the diversity, composition, and predictive function of the cecal microbiota which may have lowered the negative impact of necrotic enteritis (NE).

The effect of supplementation of multistrain probiotic preparation in combination with vitamins and minerals to the basal diet on the growth performance, carcass traits, and physiological response of broilers.

Aim:The aim of the present study was to investigate the effect of supplementation of multistrain probiotic preparation in combination with vitamins and minerals to the broiler chicken diets on their growth performance, hematological parameters, and carcass traits.Materials and Methods:Two hundred and eighty-eight Lohmann 1-day-old broiler chicks were randomly allocated to four groups, i.e., control (without additional supplementation) and three experimental treatments where basal diet was enriched by 0.1%, 0.5%, or 1% of multistrain probiotic preparation in combination with vitamins and minerals, respectively. Blood sampling was conducted on day 28, while the selected organs and eviscerated carcasses were collected on day 42.Results:Dietary supplementation did not affect (p>0.05) the final body weight, feed intake, and feed conversion ratio of broilers. Supplementation by 0.1% and 0.5% of multistrain probiotic preparation in combination with vitamins and minerals reduced (p≤0.05) heart relative weight of broilers. Dietary supplementation tended (p=0.07) to increase the relative weight of ileum and pancreas of broilers. Supplemented birds had lower (p≤0.05) numbers of leukocytes and eosinophils compared to unsupplemented birds. There were tendencies that supplementation of multistrain probiotics in combination with vitamins and minerals resulted in lower (p=0.07) counts of lymphocytes and heterophils when compared with no supplementation. Supplementation by 0.5% of multistrain probiotics in combination with vitamins and minerals resulted in lower (p≤0.05) serum concentration of uric acid when compared with control. There was no significant effect of dietary supplementation on carcass traits, pH, and drip loss of broiler breast muscles.Conclusion:Dietary supplementation of commercial broiler feeds with 0.5% of multistrain probiotic preparation in combination with vitamins and minerals was potential to improve digestive functions and physiological status of broiler chickens.

Sodium butyrate improved performance while modulating the cecal microbiota and regulating the expression of intestinal immune-related genes of broiler chickens

This study evaluated the effect of sodium butyrate (SB) on performance, expression of immune-related genes in the cecal tonsils, and cecal microbiota of broiler chickens when dietary energy and amino acids concentrations were reduced. Day-old male Ross 708 broiler chicks were fed dietary treatments in a 3 × 2 factorial design (8 pens per treatment) with 3 dietary formulations (control diet; reduction of 2.3% of amino acids and 60 kcal/kg; and reduction of 4.6% of amino acids and 120 kcal/kg) with or without the inclusion of 0.1% of SB. Feed intake (FI), body weight gain (BW gain), and feed conversion ratio (FCR) were recorded until 28 d of age. From 14 to 28 d, there was an interaction of nutrient density by SB (P = 0.003) wherein BW gain of birds fed SB was impaired less by the energy/amino acids reduction than unsupplemented birds. A similar result was obtained from 1 to 28 d (P = 0.004). No interaction (P < 0.05) between nutrient density by SB was observed for FCR. Nutritional density of the diets and SB modified the structure, composition, and predicted function of the cecal microbiota. The nutritionally reduced diet altered the imputed function performed by the microbiota and the SB supplementation reduced these variations, keeping the microbial function similar to that observed in chickens fed a control diet. The frequency of bacterial species presenting the butyryl-CoA: acetate CoA-transferase gene increased in the microbiota of chickens fed a nutritionally reduced diet without SB supplementation, and was not changed by nutrient density of the diet when supplemented with SB (interaction; P = 0.01). SB modulated the expression of immune related genes in the cecal tonsils; wherein SB upregulated the expression of A20 in broilers fed control diets (P < 0.05) and increased IL-6 expression (P < 0.05). These results show that SB had positive effects on the productive performance of broilers fed nutritionally reduced diets, partially by modulating the cecal microbiota and exerting immune-modulatory effects.

Effect of microencapsulated sodium butyrate dietary supplementation on growth performance and intestinal barrier function of broiler chickens infected with necrotic enteritis

Necrotic enteritis (NE) is an enterotoxigenic disease caused by Clostridium perfringens that results in substantial economic losses to the global poultry industry. Here, we investigated the effects of dietary microencapsulated sodium butyrate (MSB) on the growth performance and intestinal barrier function of broiler chickens co-infected with Eimeria spp. and C. perfringens. Chickens were fed, from hatch, either a diet supplemented with MSB, or with a non-supplemented control diet, and were either left uninfected or orally infected with mixed strains of Eimeria species at 12 d of age, followed by an oral inoculation with C. perfringens at 16, 17, and 18 d of age. NE-infected chickens fed MSB-supplemented diets had greater body weight (BW), improved average daily gains (ADG), and higher feed conversion ratios (FCR) than NE-infected birds fed unsupplemented diets. Increased jejunal villus height, reduced duodenal lesion scores, reduced cecal Escherichia coli and C. perfringens counts, and reduced liver C. perfringens load were also observed in the NE-infected, MSB-supplemented chickens as compared to the NE-infected, unsupplemented birds. NE infection downregulated claudin-4, ZO-1, occludin, LEAP-2, and mucin-2 in the jejunum. However, MSB-fed birds infected with NE had significantly upregulated claudin-1, claudin-4, ZO-1, occludin, LEAP-2, and mucin-2 levels in the jejunum as compared with infected birds fed the non-supplemented diet. We have thus demonstrated that the administration of MSB alleviates intestinal mucosal barrier injury of broiler chickens infected with NE.

Post‐fledging survival of Little Owls Athene noctua in relation to nestling food supply

Among the range of determinants of post‐fledging survival in altricial birds, the energy supply to the growing juveniles is likely to play a central role. However, the exact mechanisms shaping post‐fledging survival are poorly understood. Using a food supplementation experiment, we determined the effect of variation in food supply on the survival of juvenile Little Owls Athene noctua from hatching to 2 months post‐fledging. Experimental broods were food‐supplemented for 36 days during the nestling and the early post‐fledging period. The fate of 307 juveniles (95 of them provided with extra food) was determined by nest monitoring and radiotelemetry. In unsupplemented birds, the rates of survival measured at 5‐day intervals were lowest during the nestling stage, remained low during the early post‐fledging stage and steadily increased after about 2 weeks post‐fledging. Food supplementation substantially increased nestling survival, but we detected no direct treatment effect on post‐fledging survival. Instead, we found a strong indirect effect of food supplementation, in that fledglings of good physical condition had markedly higher chances of surviving the post‐fledging period compared with those in poor condition. Experimental food supplementation increased survival over the first 3 months from 45% to 64.6%. This suggests that energy reserves built up during the nestling stage influence post‐fledging survival and ultimately parental reproductive output. The low nestling and post‐fledging survival shows that the early life‐history stages constitute a crucial bottleneck of reproductive ecology in Little Owls. The strong treatment effects on the number of independent offspring indicate that natural variation in food supply is an important determinant of spatio‐temporal patterns in Little Owl demography.

Concentrations of calcium and 25-hydroxycholecalciferol (vitamin D3) in plasma of wild kākāpō (Strigops habroptilus) living on two islands in New Zealand

AIMSThis preliminary study had the objectives of describing the concentrations of ionised calcium and 25-hydroxycholecalciferol (25(OH)D3) in the blood of wild kākāpō (Strigops habroptilus) living on two islands in New Zealand, and to determine the effects of supplementary feeding on these blood parameters.METHODSBlood samples were obtained from 33 kākāpō living on two offshore islands during routine health checks in 2015. Birds on Hauturu were sampled in May (n=5) and birds on Whenua Hou were sampled in July (n=15) and November (n=26). Of the birds sampled on Whenua Hou in November, 15 received supplementary food prior to sampling. Samples were analysed for pH, and concentrations of ionised calcium, total calcium, phosphorous, total protein, albumin, globulin, uric acid and 25(OH)D3.RESULTSConcentrations of ionised calcium did not differ between unsupplemented birds on the two islands, nor between supplemented (median 1.17 (95% CI=1.12–1.20) mmol/L) and unsupplemented (median 1.09 (95% CI=1.08–1.14) mmol/L) birds sampled in November on Whenua Hou (p>0.05), and were comparable with published normal ranges for other psittacines. Concentrations of 25(OH)D3 did not differ between unsupplemented birds on the two islands (p>0.05), but were higher in supplemented (median 8.00 (95% CI=4.76–8.45) nmol/L) than unsupplemented (median 0.00 (95% CI=−0.16–0.48) nmol/L) birds on Whenua Hou (p<0.001). All values were much lower than published ranges for healthy psittacines. There was no difference between male and female birds on Whenua Hou for any parameter measured (p>0.05).CONCLUSIONS AND CLINICAL RELEVANCEThe calcium status of the kākāpō in this study was comparable to other wild psittacines, however concentrations of 25(OH)D3 were much lower. The concentrations of 25(OH)D3 may be within the normal range for the species, however further data are required to confirm this. The significant increase in concentrations of 25(OH)D3 in supplementary fed birds suggests that this food was providing more of the nutrient than the wild diet at that time of year, although the effects of this are unknown. Further investigation is required into the calcium and vitamin D3 status of kākāpō, across a wider range of locations, seasons and ages. This would help define normal ranges for these parameters, allow interpretation in clinically abnormal individuals, and guide the refinement of supplementary foods. This information would, therefore, assist the future conservation management of this critically endangered species.

Effects of dietary yeast β-glucans supplementation on growth performance, gut morphology, intestinal Clostridium perfringens population and immune response of broiler chickens challenged with necrotic enteritis

Necrotic enteritis (NE) is an enterotoxemic disease caused by Clostridium perfringens that results in substantial economic losses to the global poultry industry. This study was conducted to investigate the effects of dietary yeast β-glucans (YG) on growth performances, gut morphology, intestinal C. perfringens population, endogenous antimicrobial peptide expression, and humoral immune response of broiler chickens infected with NE. A total of 240 one-day-old male broiler chicks were randomly assigned to a 2×2 factorial arrangements of treatments with two dietary glucan levels (0 or 200mg/kg of diet) and two disease challenge status (control or NE challenged). NE model was induced via oral inoculation of mixed strains of Eimeria species at 12 d of age, followed by an oral inoculation with C. perfringens at 16, 17 and 18 d of age. Infected birds fed the glucan-supplemented diet had significantly increased body weight (13 to 21 d, 0 to 42 d), significantly improved feed efficiency (13 to 21 d, 21 to 42 d), increased antibody levels against C. perfringens and improved villi height and villi height to crypt depth ratio. In addition, infected birds that were supplemented with YG had markedly reduced intestinal C. perfringens numbers, and NE gut lesion scores compared with infected birds fed unsupplemented diet. Moreover, YG supplementation increased gene expression of Cath-2, AvBD-4, and AvBD-10 expression at the early infection stage and Cath-1, Cath-2, and AvBD-1 at the later infection stage in the gut compared with unsupplemented birds. Decreased AvBD-10 and LEAP-2 mRNA levels were observed at the later infection stage in the glucan-supplemented birds when compared with that in the non-supplemented control group. In conclusion, yeast β-glucans supplementation improved intestinal health of broiler birds challenged with C. perfringens-induced necrotic enteritis.

Hops β-acids and zinc bacitracin affect the performance and intestinal microbiota of broilers challenged with Eimeria acervulina and Eimeria tenella

Abstract The objective of this study was to evaluate the effects of dietary hops β-acids on the productive performance and intestinal microbiota of broilers challenged with Eimeria acervulina and Eimeria tenella. 1440 broiler chicks were allocated in a randomized design with 6 treatments and 6 replicates of 40 birds/pen. The treatments were: basal diet, negative control (NC); basal diet supplemented with 30 mg/kg of zinc bacitracin, positive control (PC); NC + challenge; PC + challenge; NC + 30 mg/kg of hop β-acids + challenge; and NC + 240 mg/kg of hop β-acids + challenge. At 14 days of age, the birds were challenged with Eimeria acervulina and E. tenella. The performance was evaluated and the analysis of the intestinal microbiota was performed. The coccidiosis infection impaired (P = 0.001) the weight gain, feed intake and the feed conversion ratio in the first week after the challenge. In the second week after the challenge, the effects were less evident. The feed conversion ratio was better (P = 0.05) in the challenged birds, compared to the non-challenged, in the last two weeks of the experiment. Considering the overall experimental period, the weight gain and feed intake were higher in the PC compared to the NC, and among the challenged birds, the feed conversion ratio was better in those receiving zinc bacitracin and hops β-acids in the diet. Among the challenged birds, the zinc bacitracin and both levels of hops β-acids decreased (P = 0.009) Clostridiales amount when compared to the unsupplemented birds, in the small intestine at 21 days of age. In addition, the challenge decreased the Staphylococcus (P = 0.01) and Enterococcus (P = 0.001) amounts; however, both additives tended to increase Enterococcus amount (P = 0.09). At 35 days of age, the both levels of β-acids increased Clostridiales (P = 0.04) and decreased Lactobacillus (P = 0.008) in the small intestine, among the challenged birds. At this age, the challenge tended to increase (P = 0.07) Bacteroides amount in the ceca of broilers, and the higher level of hops β-acids tended to decrease (P = 0.09) its amount when compared to the lower level. In conclusion, the hops β-acids showed similar positive effects to those obtained with zinc bacitracin supplementation on the productive performance changed the intestinal microbiota of challenged birds and have potential to replace the antimicrobial performance enhancers in the diets of broilers.

Effects of a blend of essential oils on broiler performance and intestinal morphology during coccidial vaccine exposure

SUMMARY a 2 × 2 factorial experiment (8 pens/treatment, 26 birds/pen) was conducted with 2 doses of a coccidial vaccine [1× or 5× (Paracox-5, schering-Plough animal Health, Uxbridge, UK)], administered at 1 d of age) with or without supplementation (125 g/1,000 kg) with a phytogenic feed additive containing a blend of essential oils from oregano, anise, and citrus peel [Biomin P.e.P. 125 poultry (Biomin gmbH, Herzogenburg, austria); eO]. Within each pen, 13 birds received the coccidial vaccine, whereas the remainder were naturally exposed through the recycling of oocysts in the litter. in pens of birds receiving the higher (5×) dosage of coccidial vaccine, the BW of broilers decreased by up to 2.7% (P = 0.08), but feed-to-gain ratio (FCR) and mortality at 27 d of age (P > 0.05) were not affected. Between d 14 and 27 within pens of birds receiving the 1× dosage of coccidial vaccine, those that were fed eO had a 5.6% increase in BW gain (P 0.05). Birds naturally exposed in pens receiving the higher (5×) dosage of coccidial vaccine had an 11% reduction in ileal crypt depth (P 0.05). in naturally exposed birds with pen-mates given the 1× dosage of coccidial vaccine, birds fed eO had 12% longer villi than did unsupplemented birds (P < 0.05), with 30% more goblet cells and 23% more goblet cells/10 μm of villus length (P < 0.05). in conclusion, the dosage of coccidial vaccine had an impact on BW, intestinal turnover rate, and crypt depth, whereas dietary supplementation with the eO additive increased villus length and goblet cell density, which may have created an improved barrier against pathogens during a mild coccidial exposure.

Phytase and 1alpha-hydroxycholecalciferol supplementation of broiler chickens during the starting and growing/finishing phases

Supplemental 1alpha-hydroxycholecalciferol (1alpha-OHD3) has been shown to have qualitatively similar and quantitatively additive effects to exogenous phytase. Two experiments were conducted from 0 to 35 d in floor pens to determine the additive effect of phytase and 1alpha-OHD3 when supplemented to Ca- and P-deficient diets. In both experiments, at least 4 replicates per treatment (50 chicks per replicate) were used. Corn-soybean-meal-and soybean-oil-based diets were fed and birds were raised in a house impervious to ultraviolet light. During the starter phase (ST), from 0 to 18 d, chicks were fed a 23% CP diet containing 0.60% Ca and 0.47% total P (tP). During the grower/finisher phase (GF), from 19 to 35 d, birds were fed a 19% CP diet containing 0.30% Ca and 0.37% tP. A combination of 1,000 phytase units/kg of Natuphos phytase and 5 microg/kg of 1alpha-OHD3 (P+1A) was supplemented to some of the feed during the ST and GF. Diets containing adequate Ca and P were also fed during the ST (0.90% Ca, 0.68% tP) and GF (0.80% Ca, 0.67% tP). Performance characteristics and the incidence of rickets and tibial dyschondroplasia were measured at 18 and 35 d. In experiment 1, unsupplemented chicks performed well but had considerable leg problems. Chicks fed P+1A during the ST or GF did not perform as well as birds fed P+1A throughout. Birds fed P+1A throughout performed as well birds fed the adequate diets without any indication of leg problems. In experiment 2, unsupplemented birds performed similarly to unsupplemented birds in experiment 1. However, chicks fed the supplements or the control diets did not perform as well or accumulate as much bone ash as birds in experiment 1, although the diets were formulated identically in both experiments. Diets with as little as 0.30% Ca and 0.37% tP appear to be adequate for broilers older than 18 d if supplemented with the correct amounts of phytase and 1alpha-OHD3. However, there are unknown variables that may limit the potential of broilers in terms of bone mineralization and bone pathology, even when adequate diets are fed.

Effect of Scavenging and Supplementation of Lysine and Methionine on the Feed Intake, Performance and Carcase Quality of Improved Dual-Purpose Growing Chickens

An experiment was conducted with 192 improved dual-purpose chickens from 4 to 12 weeks of age to evaluate the effects of management system (confinement and scavenging) and amino acid supplementation (with and without lysine and methionine) of a low-protein diet on the feed and nutrient intake, performance and carcase quality of improved chickens. Mean daily dry matter (DM), crude protein and metabolizable energy intakes were higher for the confined birds (65 g, 13.3 g and 966 kJ, respectively) than for the scavenging birds (58 g, 12.0 g and 868 kJ, respectively) (p < 0.001) and higher for the unsupplemented (63.3 g, 13.0 g and 945 kJ, respectively) than for the supplemented birds (59.5 g, 12.2 g and 889 kJ, respectively) (p < 0.001). Mean DM intake was 68.0 and 54.9 g/day for the males and females (p < 0.001), respectively. Average daily weight gains (ADG) were higher for scavenging (26.9g) than for confined birds (23.9g) (p < 0.001), higher for supplemented (27.6 g) than for unsupplemented birds (23.2 g) (p < 0.001) and higher for males (27.5 g) than for females (23.3 g) (p < 0.001). Carcase, breast and thigh percentages were higher for supplemented than for unsupplemented birds (p < 0.001) and higher for scavenging than for confined birds (p < 0.001). Abdominal fat percentage was significantly lower for the scavenging treatments compared to the corresponding confined treatments (p < 0.001). Feed conversion ratios (kg feed/kg gain) and feed costs/kg gain were lower for the scavenging than for the confinement treatments, and lower for the supplemented than for the unsupplemented birds (p < 0.001). Supplementation of lysine and methionine in diets that were suboptimal in terms of protein and essential amino acids improved performance and carcase quality and reduced feed costs, in particular of the confined growers.

Nutritional quality of prebreeding diet influences breeding performance of the Florida scrub-jay.

Food supplementation studies of breeding birds have traditionally concentrated on energetic constraints on breeding performance. It is only recently that the nutritional quality of the prebreeding diet has also been considered influential. We examined the importance of specific nutrients in the prebreeding diet of the Florida scrub-jay ( Aphelocoma coerulescens). Birds were provided with one of two supplements (rich in protein and fat or rich in fat only) prior to breeding in 2000 and 2001 and their breeding performance, in relation to unsupplemented (control) birds, was examined. Birds receiving both supplements significantly advanced laying in both years, and increased clutch size in 2000 but not in 2001. Laying date explained variation in clutch size in birds on dietary supplements. Egg mass and volume declined with laying order, irrespective of dietary treatment, but birds on the high fat, high protein diet laid heavier third eggs than controls and this was independent of laying date. Laboratory analysis of 14 abandoned and unhatched eggs revealed that as egg mass increased so did the absolute amount of protein and water while fat content remained relatively fixed. Using these relationships between the masses of egg components and fresh egg mass, we calculated that heavier third eggs laid by birds on high fat and high protein, compared with those laid by controls, contained more water that may be fundamental to chick growth and survival. This is the first demonstration for an avian species that nutritional quality of prebreeding diet can simultaneously influence laying date, clutch size, and egg size and composition.

Dietary Sodium Bicarbonate, Monensin, or Coccidial Innoculation and Productive Performance of Market Turkeys on Built-Up Litter

Nicholas Large White male turkey poults, 1536 at placement and 1280 at 3 wk, were used in a pen trial on built-up litter during summer 1994 in Maryland to evaluate dietary sodium bicarbonate (SBC; 0 or 0.25%), monensin (MON; 0 or 99 ppm), or coccidial inoculation (COC; 0 or 2 Eimeria species), singly and in various combinations. Per treatment, there were eight replicate pens (5’×15’) of 24 poults each at placement and 20 poults each retained at 3 wk. All feeds had bacitracin MD at 55 ppm.Significant COC×SBC×MON interactions were found at 3 wk, and some two-variable interactions (COC×SBC, COC×MON, or SBC×MON) were observed at each age. Coccidial-inoculated tom turkeys fed dietary SBC and MON had significantly improved 3-wk weight (+0.122 lb) and mortality (-5.36% actual) compared to inoculated but unsupplemented birds. At 3 wk, inoculated turkeys without SBC or MON had 5.95% mortality, compared to 4.17% with SBC, 3.57% with MON, and 0.59% with SBC and MON (highest and lowest significantly different).Poults inoculated with coccidia at 2 wk of age via drinking water had significantly poorer performance in all parameters measured at 3, 6, and 18 wk of age than uninoculated birds, validating the coccidial stressor model. Dietary MON significantly enhanced most or all performance parameters at each age. Dietary SBC significantly improved 3-wk and 6-wk body weights and feed conversions, and 18-wk mortality (P<.054; 8.64 vs. 6.07%), compared to diets with no SBC.

Effects of Food Supplementation on the Timing of Nest Initiation in Belted Kingfishers

Numerous food supplementation experiments have tested the hypothesis that timing of reproduction in birds is limited by energy constraints. These studies have generally concluded that food availability is the primary proximate factor affecting the timing of nesting in birds. None of these studies, however, has examined the relationship between food availability and the timing of nesting in piscivorous birds. To determine whether food was the primary proximate factor affecting timing of nest initiation in the piscivorous Belted Kingfisher (Ceryle alcyon), we conducted a food supplementation experiment from 1993 through 1995; additional descriptive data were collected in 1992. Belted Kingfishers that nested early had heavier nestlings and were more likely to renest, in the event of nest failure, than were late-nesting birds. This indicates a reproductive advantage in early nesting. In 1994 and 1995, when we began the feeding treatment early in the prebreeding season (8 March) and provided enough fish to meet the estimated energy requirements of a pair of kingfishers (90 g/d), nests of supplemented birds were initiated earlier than those of unsupplemented birds as predicted by the energy constraint model. In 1993, when we began the feeding treatment later (20 April) and provided less fish (20–30 g/d), there was no difference in the initiation dates of supplemented and unsupplemented nests. Although these data support the primary prediction of the energy constraint model, two patterns in our data were not explained by this model. First, few unsupplemented nests were initiated early in the breeding season relative to an unmanipulated reference population. Second, no supplemented nests were initiated outside the range of nesting dates recorded in our unmanipulated reference population. Based on these patterns, we argue that variation in arrival time of females on the breeding grounds, coupled with their selection of territories based on food availability, offers a feasible and testable alternative to the energy constraint model. This habitat selection model predicts that food availability influences the location of reproduction of individuals, but does not alter the timing of their reproduction. A literature review revealed few data that could distinguish the energy constraint and habitat selection models. We think that it is important to consider the habitat selection alternative before concluding that the results of food supplementation studies support the energy constraint model. We suggest that future studies use spatial and temporal controls to partition variation in nest initiation dates into multiple causes (e.g., energy constraints, habitat selection).

EFFECTS OF FOOD SUPPLEMENTATION ON THE TIMING OF NEST INITIATION IN BELTED KINGFISHERS

Numerous food supplementation experiments have tested the hypothesis that timing of reproduction in birds is limited by energy constraints. These studies have generally concluded that food availability is the primary proximate factor affecting the timing of nesting in birds. None of these studies, however, has examined the relationship between food availability and the timing of nesting in piscivorous birds. To determine whether food was the primary proximate factor affecting timing of nest initiation in the piscivorous Belted Kingfisher (Ceryle alcyon), we conducted a food supplementation experiment from 1993 through 1995; additional descriptive data were collected in 1992. Belted Kingfishers that nested early had heavier nestlings and were more likely to renest, in the event of nest failure, than were late-nesting birds. This indicates a reproductive advantage in early nesting. In 1994 and 1995, when we began the feeding treatment early in the prebreeding season (8 March) and provided enough fish to meet the estimated energy requirements of a pair of kingfishers (90 g/d), nests of supplemented birds were initiated earlier than those of unsupplemented birds as predicted by the energy constraint model. In 1993, when we began the feeding treatment later (20 April) and provided less fish (20–30 g/d), there was no difference in the initiation dates of supplemented and unsupplemented nests. Although these data support the primary prediction of the energy constraint model, two patterns in our data were not explained by this model. First, few unsupplemented nests were initiated early in the breeding season relative to an unmanipulated reference population. Second, no supplemented nests were initiated outside the range of nesting dates recorded in our unmanipulated reference population. Based on these patterns, we argue that variation in arrival time of females on the breeding grounds, coupled with their selection of territories based on food availability, offers a feasible and testable alternative to the energy constraint model. This habitat selection model predicts that food availability influences the location of reproduction of individuals, but does not alter the timing of their reproduction. A literature review revealed few data that could distinguish the energy constraint and habitat selection models. We think that it is important to consider the habitat selection alternative before concluding that the results of food supplementation studies support the energy constraint model. We suggest that future studies use spatial and temporal controls to partition variation in nest initiation dates into multiple causes (e.g., energy constraints, habitat selection).

Effects of supplemental ascorbic acid on the energy conversion of broiler chicks during heat stress and feed withdrawal

The objectives of this study were 1) to determine the effects of supplemental ascorbic acid (AA) on the energy conversion of broiler chicks maintained at thermoneutral and potential heat stress temperatures using indirect convective calorimetry; and 2) to determine whether changes in energy conversion are reflected in changes in lipid metabolism. In Experiment 1, 120 2-d-old cockerels, housed in two identical environmental chambers, were maintained under constant light (2.0 +/- 0.2 fc) and recommended thermal conditions (29.6 +/- 0.8 C; 33.4 +/- 8.0% RH) and consumed water and feed ad libitum. Beginning on Day 8 posthatch, one-half of the birds inside each chamber were randomly assigned and received feed supplemented with AA. Beginning on Day 9 posthatch, the temperature inside one chamber was increased to 34 C whereas the other chamber remained thermoneutral. This design resulted in four treatments: 1) thermoneutral (TN: 27.7 +/- 0.8 C; 40.9 +/- 9.4% RH) and 0 mg AA/kg feed (ppm); 2) TN and 150 ppm AA; 3) heat stress (H: 33.8 +/- 0.5 C; 43.3 +/- 7.4% RH) and 0 ppm AA; or 4) H and 150 ppm AA. Also beginning on Day 9 posthatch, birds were randomly assigned to one of three identical, indirect convective calorimeters designed to accommodate TN or H. Oxygen consumption, carbon dioxide production, respiratory quotient, and heat production were evaluated daily for 8 h, through Day 17 posthatch. Following calorimetric measurement, birds were returned to their respective caging unit/chamber for the remainder of the study. Weight gain, feed intake, and gain: feed were also measured over the 9-d study. Heat exposure depressed (P < 0.05) weight gain, feed intake, and gain:feed. Ascorbic acid increased (P < 0.10) weight gain. Oxygen consumption and carbon dioxide and heat production per kilogram0.75 decreased (P < 0.05) with age with no change in the respiratory quotient. Heat exposure lowered (P < 0.001) the respiratory quotient. A temperature by AA interaction was detected in which heat-exposed birds expressed lower (P < 0.10) respiratory quotients when consuming the AA-supplemented diet. In Experiment 2, 18 2-d-old cockerels, housed in an environmental chamber, were maintained under constant light and recommended thermal conditions (29.3 +/- 0.4 C; 41.4 +/- 3.3% RH) and consumed water and feed ad libitum. On Day 9 posthatch, birds were deprived of feed for 24 h with ad libitum access to water supplemented with either 0 or 400 mg AA/L. Blood samples were obtained from each bird before and after feed withdrawal and supplementation. Supplemented birds exhibited elevated (P < 0.01) plasma AA, levels that were not affected by feed deprivation. Feed deprivation increased (P < 0.0001) plasma beta-hydroxybutyrate with no effect of AA, and decreased (P < 0.05) plasma triglycerides in the unsupplemented birds. A feed withdrawal by AA interaction was detected in which plasma triglycerides remained elevated in birds supplemented with AA. These data suggest that supplemental AA influences body energy stores that are used for energy purposes during periods of reduced energy intake.