RESUMEN

This study evaluated the effects of breed on voluntary preferential intake of two sources of Cu, Mn, and Zn when added to white salt-based trace mineral supplement (days 0 to 55; experiment 1) and protein supplement (days 56 to 112; experiment 2). On day 0, Nelore and ½ Angus × ½ Nelore heifers (n = 20/breed) were stratified by breed, body weight (BW = 347 ±â€…82 kg), and age (12 to 30 mo), and randomly allocated into 1 of the 40 drylot pens (1 heifer/pen). Both experiments were divided into washout (days 0 to 27 in experiment 1 and days 56 to 83 in experiment 2) and preferential intake periods (days 28 to 55 in experiment 1 and days 84 to 112 in experiment 2). During the respective preferential intake period, heifers were provided simultaneous free-choice access to sulfate (SUL) and hydroxychloride (HYD) sources of Cu, Mn, and Zn mixed into salt-based trace mineral supplements from days 28 to 55 (experiment 1) and then protein supplements from days 84 to 112 (experiment 2). Heifers were provided free-choice access to Tifton 85 (Cynodon sp.) hay from days 0 to 112. Effects of breed × source × day of the study were detected (P ≤ 0.05) for daily trace mineral intake from days 28 to 56 and days 84 to 112. Angus × Nelore heifers consumed a greater amount of SUL vs. HYD supplements on days 31 to 33 (P = 0.02) and HYD vs. SUL supplements on days 37 to 42 (P ≤ 0.02), whereas Nelore heifers consumed more HYD vs. SUL supplements on days 31 to 33 and 43 to 51 (P ≤ 0.05). Both breeds consumed (P ≤ 0.05) a greater amount of protein supplement containing HYD vs. SUL from days 84 to 112, but the differences in protein supplement intake increased (P ≤ 0.04) in greater magnitude for Nelore vs. Angus × Nelore heifers. Supplement intake coefficient of variation (CV) from days 28 to 41 and days 84 to 97 tended (P = 0.06) to be greater for Nelore vs. Angus × Nelore heifers. Effects of breed × source were detected (P = 0.02) for supplement intake CV from days 84 to 112. Intake CV of supplements added with HYD did not differ (P ≥ 0.40) between Nelore vs. Angus × Nelore heifers but was greater (P < 0.01) for Nelore vs. Angus × Nelore heifers fed SUL supplements. Overall, Nelore heifers had greater preferential intake for mineral and protein supplements containing hydroxychloride vs. sulfate sources compared to Angus × Nelore heifers. Hydroxychloride sources encouraged voluntary intake and reduced variation in supplement consumption compared to SUL sources of the same metals.

RESUMEN

This study was carried out to evaluate the effects of supplementation with different levels of copper (Cu) and zinc (Zn), using two mineral sources (sulphate and hydroxy forms), on the bone characteristics, skin strength/elasticity, and haematological parameters of broilers. A total of 1792 1-day-old male Cobb-500 broiler chickens were randomly distributed among eight dietary treatments, using Cu sulphate (CSM) or hydroxychloride (CHC), and Zn sulphate (ZSM) or hydroxychloride (ZHC). The dietary treatments were as follows: (1) low-CSM/high-ZSM, (2) high-CSM/high-ZSM, (3) low-CHC/low-ZHC, (4) low-CHC/medium-ZHC, (5) low-CHC/high-ZHC, (6) high-CHC/low-ZHC, (7) high-CHC/medium-ZHC, and (8) high-CHC/high-ZHC. On Day 42, blood samples were collected from one bird/pen to analyze the haematological parameters. Finally, two birds/pen were slaughtered, and the tibia and femur were collected to analyze the quality of bone and skin. The means were subjected to ANOVA and, when significant, compared by Tukey's test (p < 0.05) or Dunnett's (p < 0.05) test. The haematological parameters were not influenced by mineral supplementation. However, the inclusion of low ZHC enhanced the skin strength compared to high ZHC (p = 0.046). Furthermore, the bone mineral density of the tibia proximal epiphysis, tibia ash and tibia mineral content were positively improved with supplementation of low-CHC/medium-ZHC compared to high-CHC/medium-ZHC. This study demonstrated that hydroxy compounds are potential alternatives for replacing sulphate supplements in broiler diets. Moreover, among the Cu and Zn levels, the low CHC (15 mg/kg) and medium ZHC (100 mg/kg) improved bone development and skin integrity, suggesting that the combination of Cu and Zn can be a nutritional strategy to prevent the incidence of leg disorders in broilers.

Asunto(s)

Oligoelementos , Zinc , Animales , Masculino , Alimentación Animal/análisis , Pollos , Cobre/farmacología , Dieta/veterinaria , Suplementos Dietéticos , Manganeso , Minerales , Sulfatos , Zinc/farmacología