Feeding low dietary levels of organic trace minerals improves broiler performance and reduces excretion of minerals in litter

1. This experiment was conducted to evaluate the effect of organic and inorganic trace minerals in diets fed to 1872, one-day-old male Ross 708 broiler chicks. Two sources of supplemental trace minerals (inorganic or organic) and four trace minerals levels (12.5%, 25.0%, 37.5% or 50.0%) plus a positive control containing inorganic minerals at 100% of recommended levels according to Brazilian industry standards, were used in the diets. 2. When analysed with mineral source as the main factor, broilers fed diets containing organic minerals had better feed conversion (FCR) throughout the trial, until 48 d of age (1.754 organic vs. 1.783 inorganic; P < 0.05), improved liveability at 48 d (95.8% organic vs. 93.6% inorganic; P < 0.05) and higher weight gain at 48 d (3.941 kg organic vs. 3.881 kg inorganic; P < 0.05) compared to the inorganic trace mineral diets. At lower dietary inclusion levels (12.5% and 25%) the organic mineral-fed birds had a four-point improvement in FCR (P < 0.05). 3. Feeding organic minerals improved tibial ash at 48 d from 49.5% to 51.25% (P < 0.05). The P and Ca in the tibia at 48 d were significantly (P < 0.05) higher for the birds fed organic minerals (Ca: 17.4% vs. 18.7%; P: 8.8% vs. 9.4%, respectively). The lower levels of trace minerals in feed reduced the mineral concentration of Zn, Cu and Mn in the faeces and, hence, in the litter (P < 0.05). 4. Feeding organic minerals promoted a small, but statistically significant, drop in pH of breast meat compared to inorganic minerals at 48 d (5.83 vs. 5.86, respectively; P < 0.05). The organic mineral diets reduced drip loss in breast meat compared to inorganic trace mineral supplementation at 32 d of age, but not in older birds (2.46% vs. 3.77%, respectively; P < 0.05). 5. Oxidation status, measured by superoxide dismutase activity in breast muscle at 48 d of age, significantly increased with mineral inclusion levels (P < 0.001), irrespective of source. 6. It was concluded that the use of organic minerals, even at low levels in the diet, is beneficial for broiler performance and reduces the excretion of minerals in litter.

Genetic analysis of leg problems and growth in a random mating broiler population

Improvement in growth has been widely reported as the cause of increased incidence of leg problems in broiler chickens. We report herein the genetic relationship between growth and leg problems in a random mating broiler control population. The traits studied were valgus (VL), varus (VR), and tibial dyschondroplasia (TD), which were expressed on a binary scale of 0 (normal) and 1 (abnormal); growth rates from 0 to 4 wk (BWG 0-4) and from 0 to 6 wk of age (BWG 0-6); and residual feed intake from 5 to 6 wk of age (RFI 5-6). A threshold-linear mixed model was employed for the joint analysis of the categorical and linear traits. Incidences of VL, VR, and TD were 26, 4, and 2%, respectively. Heritability of leg problems ranged from 0.11 to 0.13. Phenotypic correlations alluded to an unfavorable relationship between growth and leg problems; however, the genetic relationship between growth and leg problems was extremely weak, ranging from 0.01 to 0.08. There is, therefore, a basis for genetic improvement in leg problems. However, improved management practices would also be important to reduce incidence of leg problems in broiler chickens.