Morphological and physiological features in small ruminants: an adaptation strategy for survival under changing climatic conditions.

Climate change due to natural human activity is a significant global phenomenon affecting the sustainability of most countries' livestock industries. Climate change factors such as ambient temperature, relative humidity, direct and indirect sun radiation, and wind have significant consequences on feed, water, pasture availability, and the re-emergence of diseases in livestock. All these variables have a considerable impact on livestock production and welfare. However, animals' ability to respond and adapt to changes in climate differs within species and breeds. Comparatively, small ruminants are more adaptive to the adverse effects of climate change than large ruminants in terms of reproduction performance, survival, production yield, and resistance to re-emerging diseases. This is mainly due to their morphological features against harsh climate effects. Tropical breeds are more adaptive to the adverse effects of climate change than small temperate ruminants. However, the difference in morphological characteristics towards adaptation to the impact of climate change will guide the development of suitable policies on the selection of breeding stock suitable for different regions in the world. The choice of breeds based on morphological features and traits is an essential strategy in mitigating and minimizing the effects of climate change on small ruminants' production and welfare. This review highlights the adaptive morphological features within and among breeds of small ruminants toward adaptation to climate change.

Meta-analysis of the inclusion of leaf meals in diets of broiler chickens.

The effects of leaf meals on growth performance of broiler chickens have been evaluated in different studies. However, no consensus has been obtained due to the variability of the results. The present study, therefore, aimed to provide a meta-analysis of randomized controlled trials examining the effects of feeding leaf meals on growth performance of broiler chickens. Literature was searched using Google Scholar, Science Direct, Scopus, and CAB Abstracts. References from eligible studies were also thoroughly reviewed to identify additional studies. Keywords used for searching the articles were leaf meals, broilers, growing, finishing, and performance. The response measures extracted from individual studies for analysis were average daily feed intake (ADFI), average daily gain (ADG), feed conversion ratio (FCR), sample size, and standard error of the mean. Eighteen studies were included in the meta-analysis. Average daily feed intake, ADG, and FCR responses to leaf meal-based diets average - 4.82 g, - 5.44 g, and 0.40, respectively. Combining the effect size estimates, our data were highly heterogeneous for ADFI (98.57%) and FCR (81%), and a moderate heterogeneity for ADG (65.11%). Evidence of publication bias was visually confirmed for ADFI, ADG, and FCR from the funnel plots. However, using the weight-function model did not show any evidence of publication bias for ADG (P > 0.05). The meta-analysis study has indicated that leaf meals can positively influence growth performance in chickens.

Replacement value of cassava for maize in broiler chicken diets supplemented with enzymes.

OBJECTIVE: Pellet durability, particle size distribution, growth response, tibia bone characteristics and energy retention were measured to evaluate cassava as an alternative energy source to replace maize in broiler diets with or without Ronozyme (A+VP) enzyme composites. METHODS: A total of 480 one-day broiler chicks were randomly assigned to 8 treatments in a 4×2 factorial arrangement. Four levels of cassava: (0%, 25%, 50%, 75%) and 2 levels of enzymes (0 and 500 g/tonne) were used. Each treatment was replicated six times, with ten birds per replicate. RESULTS: The particle size distribution in the diets showed an increasing trend of small particles with increase in cassava level. Pellet durability decreased (p<0.05) with cassava inclusion. Feed intake was highest in birds fed diets with medium cassava level at 1 to 24 d and 1 to 35 d of age. The body weight gain of birds reduced (p<0.037) as cassava level increased, but it increased (p<0.017 when enzymes were added. The feed conversion ratio was high (p<0.05) when cassava level was increased, but it reduced (p<0.05) when enzymes were added. The dressing percentage (DP), and weight of drumsticks reduced (p<0.05) with increasing cassava level. Enzyme supplementation increased (p<0.05) DP, and weight of breast, thighs and drumsticks. Ash content, weight, length, width, and bone strength decreased (p<0.05) when cassava level was increased, however, they were increased with enzyme addition. The contents of Ca, K, and Zn were raised (p<0.001) with increasing cassava level. Enzyme inclusion increased (p<0.001) all mineral contents in tibia bones. Body fat and energy retained as fat decreased (p<0.001) as cassava level increased. Enzyme inclusion increased (p<0.05) body protein content and energy retained as protein. CONCLUSION: Although broiler performance was depressed by high levels of cassava inclusion, it was not affected by low levels, which further improved by enzyme supplementation.

Influence of dietary supplementation of autolyzed whole yeast and yeast cell wall products on broiler chickens.

OBJECTIVE: This study evaluated the effect of yeast products on growth performance, visceral organ weights, endogenous enzyme activities, ileal nutrient digestibility and meat yield of broiler chickens fed diets containing autolyzed whole yeast (WY) and yeast cell walls (YCW) at varying levels of inclusion. METHODS: Nine dietary treatments consisting of WY or YCW included at 0.5, 1.0, 1.5, or 2.0 g/kg diet and a control diet without yeast supplementation was used in the experiment. Each of the nine treatments was replicated six times with nine birds per replicate. Birds were housed in cages, in climate-controlled rooms and fed starter, grower and finisher diets. RESULTS: There was an improvement (p<0.05) in body weight gain and feed conversion ratio on d 10, 24, and 35 for birds fed 1.0 to 2.0 g/kg WY or YCW diet. Small intestine weight was heavier on d 10 and 24 for birds on higher levels of WY and YCW compared to the control group. On d 10 and 24, there was a significant increase (p<0.05) in tissue protein content and pancreatic enzyme activities (trypsin and chymotrypsin) of birds on 1.5 to 2.0 g/kg WY and YCW diets compared to the control group. Compared to the control group, birds on WY (2.0 g/kg diet) and YCW (at 1.5 and 2.0 g/kg diet) had better (p<0.05) protein digestibility on d 24. On d 35, there was significant improvement (p<0.05) in percentage of carcass, absolute and relative breast weight for broiler chickens fed WY and YCW mostly at 2 g/kg diet compared to birds on the control diet. CONCLUSION: Supplementation of diets with autolyzed WY and YCW products especially at 1.5 to 2.0 g/kg diet improved broiler chicken performance and meat yield through their positive effects on ileal protein digestibility and pancreatic enzyme activities.

Indigenous chicken production in Fiji Islands: knowledge, constraints and opportunities.

OBJECTIVE: The objective of the study was to understand and document socio-economic characteristics, production parameters, challenges and management practices used by Fijian households which keep indigenous chickens. METHODS: A survey involving 200 households was carried out in coastal and inland communities of Fiji's wet and semi-dry ecoregions. Data on the influence of ecoregion and location of households relative to the sea on management practices, challenges and productivity of indigenous chickens were analyzed using logistic regression and general linear model of SAS software. RESULTS: Irrespective of location relative to the sea and ecoregion, households indicated that they kept indigenous chickens for food and income generation. The Welsummer was the most (p>0.05) preferred breed. Households in the semi-dry inland communities had the largest (p<0.05) flocks compared to those in semi-dry coastal communities and the wet region. Chickens in the semi-dry region performed better (p<0.05) than those in the wet region in terms of number of clutches per year and mature live weight. Predators and feed shortages were the biggest challenges faced by households in all areas. The mongoose was ranked as the most (p>0.05) common predator followed by domestic dogs. Most households in the wet ecoregion's coastal communities housed their chickens at night, whereas communities in semi-dry ecoregion housed their chickens most of the time (p<0.05). In all regions, no households sold their chickens to commercial markets (p>0.05). Households in semi-dry ecoregion were more likely (p>0.05) to sell their chickens at the local market place. CONCLUSION: The productivity of local chickens in Fiji is low because of feed shortage, predators such as the mongoose and lack of market linkages.

Endogenous enzyme activities and tibia bone development of broiler chickens fed wheat-based diets supplemented with xylanase, ß-glucanase and phytase.

OBJECTIVE: This study assessed the effect of different levels of xylanase, ß-glucanase and phytase on intestinal enzyme activities and tibia bone development in broiler chickens fed wheat-based diets. METHODS: Twelve experimental diets were formulated using a 3×2×2 factorial design (three doses of phytase and two doses of both xylanase and ß-glucanase) and offered to 648 dayold Ross 308 male chicks having 6 replicates groups with 9 birds per replicate and lasted for 35 days. RESULTS: An interaction between the enzymes products improved (p<0.01) the activity of chymotrypsin. Protein content at d 10 was highest (p<0.001) with addition of phytase while general proteolytic activity (GPA) (p<0.02) and lipase activity (p<0.001) were decreased. At d 24, there were improvements in protein content (p<0.01) and lipase (p<0.04) with supplementation of superdose phytase. Addition of superdose phytase decreased in chymotrypsin (p<0.02), trypsin (p<0.01) and GPA (p<0.001). The optimum dose of xylanase decreased the chymotrypsin activity (p = 0.05), while the GPA (p<0.001) was increased with the optimum level of ß-glucanase. Superdose phytase supplementation at d 10 improved maltase (p = 0.05), sucrase (p<0.001) and alkaline phosphatase (p<0.001) activities in the jejunum while aminopeptidase activity was highest (p<0.005) with the low level of phytase. Protein content of jejunum mucosa was bigger (p<0.001) in birds fed superdose phytase while maltase activity (p<0.001) at d 24 was reduced by this treatment. Sucrase (p<0.04) and aminopeptidase activities (p<0.001) improved when diets supplemented with low levels of phytase. Tibia bone breaking strength was highest (p<0.04) with addition of low level of superdose phytase or optimum level of ß-glucanase. Bone dry matter content decreased (p<0.04) when diets supplemented with phytase. CONCLUSION: From the results obtained in this study, supplementation of superdose phytase was the most effective, however, the cost-benefit analysis of the use of such a dose needs to be evaluated.

Replacement value of cottonseed meal for soybean meal in broiler chicken diets with or without microbial enzymes.

A 4×2 factorial feeding trial was designed to investigate the effect of replacing soybean meal (SBM) with cottonseed meal (CSM) in wheat/sorghum/SBM-based diets fed with or without microbial enzymes in diets on the performance, visceral organ development and digestibility of nutrients of broiler chickens. Four graded levels of CSM - none (0%), low (4%, 8%, and 12%), medium (5%, 10%, and 15%), and high (6%, 12%, and 18%) of complete diets in starter, grower and finisher, respectively were fed with or without 100 mg/kg of xylanase and ß-glucanase blend. Eight isocaloric and isonitrogenous diets were formulated using least-cost method to meet the nutrient specifications of Ross 308 male broilers. Each treatment was randomly assigned to 6 replicates (10 birds per replicate). There were CSM-enzyme interactions (p < 0.05) on feed intake (FI) and weight gain (WG) in the starter phase. Enzyme supplementation improved (p < 0.05) feed conversion ratio (FCR) in the grower and finisher phases, and increased WG in growing and finishing birds. CSM inclusion reduced (p < 0.05) the weight of gizzard and proventriculus in starter chicks, while these organs were bigger (p < 0.05) in the grower phase. The test ingredient decreased (p < 0.05) small intestinal weight in starter and grower birds. The CSM increased the absolute weight of thighs (p < 0.05) while breast meat was increased (p < 0.01) by enzyme addition. Starch digestibility was improved (p < 0.01) by enzyme inclusion and decreased (p < 0.01) by CSM. Enzyme supplementation improved (p < 0.05) the ileal digestibility of gross energy and protein. The results demonstrate that CSM can substitute up to 90% SBM in broiler chicken diets without compromising performance, and the nutritive value of CSM-containing diets can effectively be improved by enzyme supplementation.

Response of broiler chickens to diets containing different levels of sodium with or without microbial phytase supplementation.

Phytate induced excessive mineral excretion through poultry litter leads to poor performance and environmental pollution. Exogenous microbial phytase supplementation to poultry diets reduce the environmental excretion of nutrient and improve bird's performance. However, excessive dietary sodium (Na) level may hinder the phytase-mediated phytate hydrolysis and negate the beneficial effects of phytase. Therefore, this experiment was conducted to investigate the effects of different concentration dietary Na on phytase activity and subsequent impact on broiler performance, bone mineralisation and nutrient utilisation. In this study, six experimental diets, consisting of three different levels of Na (1.5, 2.5, or 3.5 g/kg) and two levels of microbial phytase (0 or 500 U/kg) were formulated by using 3 × 2 factorial design. The six experimental diets were offered to 360 day-old Ross 306 male chicks for 35 days, where, each experimental diet consisted of 6 replicates groups with 10 birds. Along with growth performance, nutrient utilization, intestinal enzyme activity, dry matter (DM) content of litter and mineral status in bone were analysed. Dietary Na and phytase had no effect on bode weight gain and feed intake. Birds on the low Na diet showed higher (p < 0.05) feed conversion ratio (FCR) than the mid-Na diets. High dietary Na adversely affected (p < 0.001) excreta DM content. Phytase supplementation to the high-Na diet increased (p < 0.01) the litter ammonia content. High dietary Na with phytase supplementation improved (Na × phytase, p < 0.05) the AME value and ileal digestibility of Ca and Mg. The total tract retention of Ca, P, and Mg was reduced with high Na diet, which was counteracted by phytase supplementation (Na × phytase, p < 0.001). The diets containing mid-level of Na improved (p < 0.001) the function of Na-K-ATPase and Mg-ATPase in the jejunum. The overall results indicate that high dietary Na did not affect phytase activity but influenced the nutrient utilization of birds, which was not reflected in bird overall performance.

Energy utilization, nutrient digestibility and bone quality of broiler chickens fed Tanzania-type diets in different forms with enzymes.

A study was conducted to determine the influence of feed form and microbial enzyme supplementation on energy utilization, bone quality, and amino acid and mineral digestibility of broiler chickens. Four hundred and eighty Ross 308, day-old broiler chickens were randomly assigned to eight diets formulated from commonly used ingredients in Tanzania. A 2 (pellet or mash) × 4 (control, Axtra XB, Quantum Blue (QB) and Axtra XB + QB enzyme) factorial array in a completely randomized design having six replicates per treatment (10 birds per replicate) was used. Birds were raised in climate-controlled rooms in a 3-phase; starter (0-10 days), grower (11-24 days) and finisher (25-35 days). Apparent metabolizable energy (AME), metabolizable energy intake, net energy of production, energy retained as protein (REp), and efficiency of metabolizable energy use for energy and protein retention were higher (p < 0.05) in birds fed pelleted diets. The AME and REp was higher (p < 0.05) with enzyme supplementation. Ash content, weight, length, width and breaking strength of tibia bones were highest (p < 0.05) in birds on pelleted diets. Tibia bone traits were improved (p < 0.05) when enzymes were included, particularly in a combination of QB and Axtra XB. However, potassium, magnesium, and zinc contents were highest (p < 0.05) when QB was supplemented. Digestibility of all amino acids was higher (p < 0.05) in birds supplied with pellets and with enzyme supplementation for most amino acids, except for serine. There was a positive interaction (p < 0.05) between feed form and enzymes on lysine and phenylalanine digestibility. Digestibility of Ca, P, K, S, Zn, and Fe was higher (p < 0.05) in birds fed pelleted diets, while those on mashed diets had higher (p < 0.05) digestibility of Cu and B. The digestibility of P, K, and Zn was highest (p < 0.001) when QB was added, while Ca, P, S, and B digestibility was highest when a combination of Axtra XB + QB was applied. Pelleted diets with or without enzymes improved energy utilization, digestibility of amino acids, and minerals, and increased bone strength in broiler chickens.