Gulizia J P, Tabish R W, Vargas J I, Hernandez J R, Simões C T, Guzman E G, Rochell S J, Hauck R, Bailey M A, Dozier W A, McCafferty K W, Pacheco W J
Department of Poultry Science, Auburn University, 260 Lem Morrison Dr., Auburn, AL 36849, USA.
Department of Preventive Veterinary, Federal University of Santa Maria, Santa Maria, Rio Grande do Sul, Brazil.
Poult Sci. 2025 May 31;104(8):105385. doi: 10.1016/j.psj.2025.105385.
This 35-d experiment evaluated the effects of limestone particle size and calcium concentrations on broiler performance, tibia mineralization, and nutrient digestibility. Two thousand one hundred d-old YPM x 708 male broilers were distributed into 70 floor pens and assigned to 1 of 7 treatments (10 replicates/treatment). This experiment was a 2 × 3 + 1 factorial arrangement, including 2 limestone particle sizes (910 and 200 µm) and 3 calcium concentrations (adequate, reduced, and low), and an unchallenged control. Dietary calcium was reduced in two 0.10 percentage unit steps from adequate concentrations (i.e., breeder recommendations). All factorial treatments were enterically challenged with Eimeria spp. and Clostridium perfringens. Performance (d 17, 21, 26, and 35), tibia mineralization (d 21 and 35), and nutrient and energy digestibility (d 21 and 35) were measured. The enteric challenge reduced BW and increased feed conversion ratios (FCR; contrast, P ≤ 0.05). Broilers fed adequate and reduced calcium diets had higher BW, tibia shear strength, and tibia ash on d 35 compared to low calcium diets (main effect, P ≤ 0.05). Day 1 to 35 FCR linearly increased as dietary calcium decreased from adequate to low in the group fed 910 µm limestone, whereas in the 200 µm limestone group, only the low calcium and not the reduced calcium led to higher FCR compared with those fed adequate calcium (interaction, P ≤ 0.05). Broilers fed reduced and low calcium diets with 910 µm limestone had the highest calcium and phosphorus digestibility on d 21. With 200 µm limestone, broilers fed a low calcium diet had higher mineral digestibility (interaction, P ≤ 0.05). Day 35 apparent ileal digestible energy (AIDE) increased when broilers consumed an adequate or reduced calcium diet compared to low calcium (main effect, P ≤ 0.05). This experiment demonstrated dietary calcium concentrations 0.10 percentage units lower than recommended concentrations can maintain broiler performance, tibia mineralization, and AIDE during an enteric challenge. However, calcium concentration effects depended on limestone particle size.
这项为期35天的试验评估了石灰石粒度和钙浓度对肉鸡生产性能、胫骨矿化及养分消化率的影响。将2100只1日龄的YPM×708雄性肉鸡分配到70个地面饲养栏中，分为7种处理方式之一（每种处理10个重复）。本试验采用2×3 + 1析因设计，包括2种石灰石粒度（910和200微米）、3种钙浓度（充足、降低和低）以及一个无应激对照组。日粮钙含量从充足浓度（即种鸡推荐量）分两个0.10个百分点的梯度降低。所有析因处理组均受到艾美耳球虫和产气荚膜梭菌的肠道感染。测定了生产性能（第17、21、26和35天）、胫骨矿化（第21和35天）以及养分和能量消化率（第21和35天）。肠道感染降低了体重并提高了料重比（对比，P≤0.05）。与低钙日粮相比，在第35天，饲喂充足和降低钙日粮的肉鸡体重、胫骨剪切力和胫骨灰分更高（主效应，P≤0.05）。在饲喂910微米石灰石的组中，从第1天到第35天，随着日粮钙从充足降低到低水平，料重比呈线性增加，而在200微米石灰石组中，只有低钙组而非降低钙组的料重比高于饲喂充足钙的组（交互作用，P≤0.05）。在第21天，饲喂910微米石灰石的降低钙和低钙日粮组的肉鸡钙和磷消化率最高。对于200微米石灰石，饲喂低钙日粮的肉鸡矿物质消化率更高（交互作用，P≤0.05）。与低钙日粮相比，当肉鸡采食充足或降低钙日粮时，第35天的回肠表观可消化能量（AIDE）增加（主效应，P≤0.05）。本试验表明，日粮钙浓度比推荐浓度低0.10个百分点时，在肠道感染期间仍可维持肉鸡的生产性能、胫骨矿化及AIDE。然而，钙浓度的影响取决于石灰石粒度。
