Ruhnke Isabelle, Akter Yeasmin, Sibanda Terence Zimazile, Cowieson Aaron J, Wilkinson Stuart, Maldonado Stephanie, Singh Mini, Hughes Patrick, Caporale Dylana, Bucker Stephan, O'Shea Cormac John
School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.
Sydney School of Veterinary Science, University of Sydney, Sydney, NSW 2570, Australia.
Animals (Basel). 2021 Oct 18;11(10):2991. doi: 10.3390/ani11102991.
Laying hens require substantial quantities of calcium (Ca) to maintain egg production. However, maintaining recommended dietary Ca through inclusion of limestone may impede nutrient digestibility, including that of other minerals. It was hypothesized that providing a separate source of dietary Ca in the form of limestone grit would preserve Ca intake of hens offered diets containing suboptimal Ca concentrations. Furthermore, the impact of dietary phytase at a "superdosing" inclusion rate on the voluntary consumption of limestone grit was evaluated. One hundred and forty-four laying hens (19 weeks of age) were assigned to one of six dietary treatments in a 3 × 2 factorial arrangement comprising three dietary Ca concentrations (40, 30, and 20 g/kg) and ±dietary phytase (3500 FYT/kg diet) on an ad libitum basis for six weeks. Limestone grit (3.4 ± 1.0 mm) was provided to all hens ad libitum. Hens offered diets containing phytase consumed significantly less limestone grit = 0.024). Egg weight, rate of lay, and egg mass were unaffected by dietary treatment ( > 0.05). Egg shell weight % ( < 0.001), shell thickness ( < 0.001), and shell breaking strength ( < 0.01) decreased in line with dietary Ca levels. In summary, dietary superdosing with phytase reduced the consumption of a separate limestone source in individually housed, early lay ISA Brown hens. Egg shell quality variables but not egg production worsened in line with lower dietary Ca levels.
产蛋母鸡需要大量的钙（Ca）来维持产蛋。然而，通过添加石灰石来维持推荐的日粮钙水平可能会妨碍营养物质的消化率，包括其他矿物质的消化率。研究假设，以石灰石颗粒的形式提供单独的日粮钙源，可以保持日粮钙浓度次优的母鸡的钙摄入量。此外，还评估了“超量添加”水平的日粮植酸酶对石灰石颗粒自愿摄入量的影响。144只19周龄的产蛋母鸡被随机分配到6种日粮处理中的一种，采用3×2析因设计，包括3种日粮钙浓度（40、30和20克/千克）和±日粮植酸酶（3500菲汀酶单位/千克日粮），自由采食6周。所有母鸡均可自由采食石灰石颗粒（3.4±1.0毫米）。采食含植酸酶日粮的母鸡摄入的石灰石颗粒显著减少（P = 0.024）。蛋重、产蛋率和产蛋量不受日粮处理的影响（P>0.05）。蛋壳重量百分比（P<0.001）、蛋壳厚度（P<0.001）和蛋壳抗破碎强度（P<0.01）随日粮钙水平的降低而降低。总之，在个体饲养的、处于产蛋初期的ISA Brown母鸡中，超量添加植酸酶会减少单独石灰石源的摄入量。随着日粮钙水平的降低，蛋壳质量指标变差，但产蛋性能未受影响。
