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Abstract | This study aimed to explore the optimal level of dietary calcium for 11 to 42 day old broilers. Three hundred and sixty commercial broiler chickens were used in this study. The broiler chickens were randomly placed in 36 pens with 6 groups, each group contained 6 pens with 10 birds for each pen. Six experimental diets with different levels of calcium (Ca) were formulated to be as follows: 1.4% Ca, 1.2% Ca, 1% Ca, 0.8% Ca, 0.6% Ca and 0.4% Ca. The polynomial regression equations were used to estimate nutritional requirements of calcium. Results show the different levels of dietary calcium had quadratic impact on calcium, phosphorus, and ALP (Alkaline Phosphatase) levels in the serum (p=0.027; p<0.0001 and p=0.0006 respectively). The ash, calcium and phosphorus content of tibia were showed non-linear responses (p<0.0001) when the dietary calcium reduced from 1.4% to 0.4%. Lower calcium in the diet non-linearly increases (p<0.05) dressing percentage and relative weight of the breast and leg. The results also showed that predicted dietary calcium requirements for dressing percentage and relative weight of breast and leg were 0.86, 0.83, and 0.81% respectively. While predicted dietary calcium requirements for ash, calcium, and phosphorus content in the tibia were 0.85, 0.86, and 0.73% respectively

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ABSTRACT Objective: This research assesses whether probiotics could enhance growth performance and improve nutrient digestibility in birds fed with low-protein diets. Materials and Methods: A total of 250 1-day-old ROSS chicks were used in a completely randomized design consisting of 5 treatments with 5 replicates and 10 birds for each replicate. The experimental diets were as follows: basal diet containing 100% crude protein (CP) according to Nutrition Research Council recommendation (control diet); basal diet containing CP 10% less than the control diet low protein (LP); LP with addition of probiotic by 50 mg/kg diet (LP + P1); LP with addition of probiotics by 100 mg/kg diet (LP + P2); LP with an addition of probiotics by 150 mg/ kg diet (LP + P3). Results: Broilers fed with the control, LP + P2, and LP + P3 diets had greater body weight and weight gain than broilers fed with the LP during starter, finisher, and total periods (p < 0.01). The feed conversion ratio was the best (p < 0.01) in the control and LP + P3 treatments compared with the LP and LP + P1 treatments throughout the experiment. The European production efficiency factor was the lowest in the LP treatment compared with other treatments from 1 to 42 days. Protein efficiency ratio and protein retention were both higher in birds fed with the LP + P2 and LP + P3 diets compared to birds given the control and LP diets (p < 0.01). Conclusion: Adding probiotics to the diet remarkably improved the productive performance and nutrient digestibility of broiler-fed low-protein diets.

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The study aimed to research the genetic variation of the Awassi and Naimi sheep breeds using the two genes myostatin (MSTN) and calpastatin (CAST). Blood samples were collected from 100 animals of the two breeds, and then DNA was extracted using a commercial kit. We used the PCR and RFLP techniques to determine genotypes and allele frequencies. The results showed that the MSTN and CAST genes are polymorphic. The MSTN gene has allelic frequencies (M and m) of 0.81, 0.19, and 0.76, 0.24 in the Awassi and Naimi breeds, respectively. The frequencies of the genotypes MM, Mm, and mm in the Awassi breed were 0.70, 0.19, and 0.11, but in the Naimi breed, they were 0.67, 0.13, and 0.20, respectively. Moreover, the number of alleles observed (Na), the effective number of alleles (Ne) and observed (Ho), and expected (He) heterozygosity were found to be 3, 2.30, 0.24, and 0.35 in the Awassi breed and 2, 1.62, 0.17, and 0.26 in the Naimi breed, respectively. The allelic frequencies (M and N) of the CAST of the Awassi and Naimi breeds are 0.86, 0.14, and 0.88, 0.12, respectively. The frequencies of the genotypes MM, MN, and NN in the Awassi breed were 0.94, 0.04, and 0.02, respectively, while for the Naimi breed, they were 0.95, 0.02, and 0.03, respectively. Also, the Na, Ne, Ho, and He were found to be 2.8, 1.72, 29.6, and 28.57 in the Awassi breed and 1.10, 1.23, 0.17, and 0.15 in the Naimi breed, respectively. According to the chi-square of MSTN and CAST genes, both breeds were not in Hardy-Weinberg equilibrium balance.

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Importance of the work: Calcium (Ca) and available phosphorus (AvP) are necessary minerals that have important roles in the animals; however, increasing dietary calcium causes several health problems. Objectives: To evaluate the effect in broiler chickens of Ca:AvP ratios on the productive performance and the retention of nutrients. Materials & Methods: In total, 360 Ross 308 broilers aged 11d (mean initial body weight ± SD = 249.80 ± 10.45 g) were randomly allocated to six dietary treatments with six replicates for each treatment and 10 birds per replicate. The experimental diets contained six concentrations of calcium (1.4%, 1.2%, 1%, 0.8%, 0.6% or 0.4%) and one level of phosphorus (0.4%) that were used to form six calcium-to-phosphorus ratios (3.5:1, 3:1, 2.5:1, 2:1, 1.5:1 and 1:1, respectively). Results: The Ca:AvP ratio had a significant (p < 0.001) effect on body weight and weight gain. The feed intake was reduced (p = 0.002) for high Ca:AvP ratios (3.5:1 and 3:1) compared to the standard Ca:AvP ratio (2:1) during the grower period but this effect disappeared in later periods. The feed conversion ratio was significantly (p = 0.001) improved in birds fed the standard Ca:AvP ratio (2:1) compared to the other ratios. The production index was the highest (p < 0.001) in birds fed the standard Ca:P ratio compared to those fed other unbalanced ratios. The different Ca:AvP ratios had no significant (p < 0.05) effect on mortality percentage. The nutrients retention and jejunum morphology were impaired with high Ca:AvP ratios (3.5:1 and 3:1) compared to several other ratios (2:1, 1.5:1 and 1:1). Main finding: These results suggested that 2:1 was the best ratio between calcium and phosphorus to achieve optimum growth performance.

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This study evaluated the effect of dietary calcium (Ca) and available phosphorus (aP) restriction on growth performance, nutrients retention (ATTR), serum metabolites, and tibia in broiler chickens. A total of 720 one-day-old Ross-308 broilers were used in this study. Broilers were fed with 0 (control), 10 (L1), 20 (L2), and 30% (L3) aP-deficient starting (ST) diets during 1–10 days. In ST period, control included 6 and others included 18 replicates of 12 chicks. In post-starter (PST) period, control was still fed with standard diets, while restricted groups were divided into 3 groups and fed with L1, L2, and L3 diets. Each PST treatment included 6 replicates of 12 chicks. Data were analysed using a completely randomised design in a 1 (control)+3 × 3 factorial arrangement. Factors included aP levels in ST and PST diets. Results showed that L3 diet decreased feed intake and weight gain but increased ATTR of Ca in starter phase in compare with control group (p<.05). Retarded growth of birds was compensated in post-starter phase. The Ca, P and ALP levels in blood serum were not significantly influenced by aP levels on day 10 and day 42. The ATTR of Ca and tP on day 42, were higher in birds fed L3 diets than L2 or L1 groups (p<.05). The main effect of L3 group in both ST and PST, decreased (p<.05) tibia ash, Ca, and P in compare with L1 group. Main effect of post-starter L3 group had lowest femur breaking strength (p=.007). In general, restriction in dietary aP increased nutrients ATTR, impaired bone mineralisation and strength without affecting growth performance.

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A total of 576-day-old Ross 308 broilers chicks (male) were used to evaluate the effect of various levels of pistachio green hull aqueous extract (PHE) and Eimeria challenge on the growth performance,intestinal health and antioxidant capacity. During infection period (25−42 d), treatments included: 1) control + unchallenged (negative control, NC), 2) 200 ppm PHE + unchallenged, 3) 300 ppm PHE + unchallenged, 4) 400 ppm PHE + unchallenged, 5) control + challenged (positive control, PC), 6) 200 ppm PHE + challenged, 7) 300 ppm PHE + challenged and 8) 400 ppm PHE + challenged (with 6 replications for each treatment). The outcomes revealed that in the challenged birds, average body weight gain (ABW), daily weight gain (DWG), and feed conversion ratio (FCR) linearly improved with increasing the PHE levels (P < 0.05). Infected broilers had lower daily feed intake (DFI) compared to unchallenged birds (P < 0.05). Villus height (VH), villus height to crypt depth (VH: CD) ratio and villus surface area (VSA) reduced linearly (P < 0.05), while muscle layer thickness (MT) increased linearly in challenged birds (P < 0.05). The consumption of the PHE significantly reduced the excreta oocytes and duodenum and jejunum lesion scores in Eimeria-challenged broilers (P< 0.05). By increasing the PHE levels, total antioxidant capacity (TAC) and superoxide dismutase (SOD) levels increased (P < 0.05), while the Eimeria challenge reduced TAC, SOD, and glutathione peroxidase (GPx) levels (P <0.05). In general, the use of PHE in the broilers diet improved the antioxidant capacity, birds performance, but diminished the excreta oocytes and lesion scores with no negative effect on the intestinal morphology.