Heshmatollah Khosravinia, Mohammad Ali Edriss, Javad Pourreza, Saeid Ansari,
Volume 3, Issue 1 (4-1999)
Abstract
To estimate heritability, and genetic and phenotypic relationships and also to study the effect of sex and rearing environment on body weight, weight gain, feed consumption and feed conversion coefficient, the data from 1200 pedigreed male and female chickens from three genetic groups including 90 sires were used. The included genetic groups were crosses of native chickens and an exotic breed (group A), native chickens which were selected for two generations on the basis of 8th week body weight (group B) and a control group of native chickens (group C). All the chicks were reared up to four weeks of age on the ground in separated pens according to their sire groups. In order to calculate feed conversion coefficient, 498 chicks were placed in individual cages during four to ten weeks of age. The results showed that the cross group (A) compared to the other two groups had a higher body weight at 2, 3, 6, 8 and 10 weeks of age. Weight gain, feed conversion coefficient and consumption at periods of 4-6, 6-8, 8-10 and 4-10 weeks were also higher in the cross group. Genetic groups B and C, in spite of better performance of group B for most of the traits, did not have any significant differences for the compared traits. Estimated heritabilities on the basis of sire variance component showed that these traits were medium to highly heritable. Estimated heritabilities for feed consumption at different ages ranged from 0.15 to 0.44 which at any age was lower than that estimated for feed conversion coefficient. Genetic and phenotypic correlations between growth traits were positive and, in most of the cases, high. Correlations between nutritional traits at different ages were variable.
Y. Ebrahim Nejad, J. Pourreza,
Volume 4, Issue 1 (4-2000)
Abstract
This experiment was carried out to study the effect of ionophore drugs (Salinomycin, Lasalocid and their combination) on the performance of broiler chicks. Also their relationship with methionine (three levels) was evaluated. 1215 one-day-old commercial broiler chicks (Arian) were divided into 81 groups, 15 chicks per group, and tested in a completely randomized design with a 3×3×3 factorial experiment and three levels (0/0, recommended and 1.5 times recommended) of drugs and three levels (0.0, 1% and 0.2%) of supplemental methionine.
The results indicated that these drugs reduced body weight gain significantly (p<0.05) at 21 and 56 days of the experiment. Decreasing feed consumption and increasing feed conversion was significant (p<0.05) due to Lasalocid supplementation. Increasing drug level significantly (p<0.05) reduced body weight gain and feed intake and feed conversion was increased at 21 to 42 and 0 to 56 days of the experiment. The effect of supplemental methionine on body weight of 42 days (P<0.05) and feed conversion at 21 to 42 and 0 to 56 days (p<0.01) were significant. The interactions between drug type and drug level on body weight gain, feed consumption and feed conversion were significant (p<0.05). Lasalocid significantly (p<0.05) increased water intake. Drugs did not affect litter moisture and mortality. The results showed that Salinomycin was better than Lasalocid. Also supplemental methionine was not effective in compensating for the growth depression caused by ionophore drugs.
A. Foroozandeh, A.h. Samie, G.r. Ghorbani,
Volume 5, Issue 1 (4-2001)
Abstract
The objectives of this study include the determination of the growth potential of Naeini lambs when fed with diets varying in energy and protein concentrations and also an investigation of the influence of level of energy and/or protein intake on carcass characteristics and composition. Ninety Naeini weather lambs (initial live weight 29.89 ± 2.9 kg) were used in a 92-day feeding experiment. Animals were blocked to each of nine dietary treatments. Diets contained either 2, 2.25 or 2.5 Mcal ME/Kg DM and 11.7, 13.2 or 14.7% CP diets were fed in a 3 × 3 factorial arrangement in randomized complete blocks.
Lambs fed with high energy diets consumed significantly more feed (P<0.05) than lambs given the medium (ME) or low energy (LE) diets. The average final body weight and daily weight gain for lambs fed with HE, ME and LE diets were 41.4, 38.3, 34.5 Kg and 162, 124, 74 g/d, respectively, which were significantly different (P<0.05). Feed conversion ratio in HE group was significantly lower (8.3) than ME (10.4) or LE (14.3) groups. Energetic efficiencies and protein efficiencies were better for HE than for ME and LE diets. Increasing dietary energy significantly (P<0.05) improved energy and protein efficiencies of the diets. Dressing percentage, lean meat and eye muscle depth were significantly (P<0.05) improved with increasing levels of energy in the diet, but also increased dissectible fat. No significant changes were observed in bone percentage and body ash due to any changes in dietary energy. As the protein level of rations increased, feed conversion ratio and carcass meat percentage increased, but carcass protein percentage decreased.
