Toledo A F, Silva A P, Barbosa F V L, Barboza R D F, Oliveira I C R, Marino E D, Polizel D M, Bittar Carla M M
Department of Animal Science, "Luiz de Queiroz" College of Agriculture, University of São Paulo, Av. Pádua Dias, n 11, Piracicaba, SP, 1341-900, Brazil.
Department of Animal Production, College of Technology and Agricultural Sciences, São Paulo State University, Ilha Solteira, SP, 15385-000, Brazil.
Sci Rep. 2024 Dec 28;14(1):30762. doi: 10.1038/s41598-024-80271-y.
The inclusion of forage sources in calf diets is often discussed, and the main point debated is whether the inclusion level, particle size, source, and how forage is offered may impact gut fill and reduce body weight gain, as well as impact gastrointestinal tract development. This study aimed to determine the effects of feeding forage sources with different qualities on rumen fermentation, gut fill, and development of the gastrointestinal tract of dairy calves. Forty-eight Holstein dairy calves were blocked according to sex and body weight (BW) at 28 days of life and randomly assigned to 1 of 4 dietary treatments. Treatments consisted of a no-forage coarsely ground starter (CON) or total mixed rations containing 7.5% on DM basis of Tifton hay of either medium quality (MH) or low quality (LH) or 10% on DM basis of corn silage (CS). The nutritional content, including crude protein, NDF, lignin, and in vitro digestibility, was used as forage quality criteria. During the first 28 days of life, all calves received 3 L of whole milk twice daily, a commercial pelleted starter ad libitum, and no forage. After that, the solid diet was changed to the respective dietary treatments. Rumen samples were taken to determine rumen pH and volatile fatty acid (VFA) proportions. Calves were gradually weaned from 52 to 56 d of age, and 20 calves, 5 per treatment, were harvested two weeks after weaning. The anatomical parts of the gastrointestinal tract were weighed with and without contents, and histological analysis of rumen epithelium was conducted. The CON diet increased total VFA concentration compared to forage diets. The forage diets increased rumen pH, fecal pH, and gut fill. However, regardless of the source, the forage provision did not affect empty body weight. In addition, the forage provision increased the number of papillae in the rumen, but diets did not influence the length and width of papillae. The results suggest that 7.5% of Tifton hay, regardless of the quality, and 10% of corn silage in high-starch mixed diets benefit rumen health and promote greater gut fill without negative effects on final body weight.
犊牛日粮中粗饲料来源的问题经常被讨论，争论的主要焦点在于粗饲料的添加水平、颗粒大小、来源以及供给方式是否会影响瘤胃充盈度、降低体重增长，同时是否会影响胃肠道发育。本研究旨在确定饲喂不同质量粗饲料来源对奶牛犊牛瘤胃发酵、瘤胃充盈度及胃肠道发育的影响。48头荷斯坦奶牛犊牛在28日龄时按性别和体重进行分组，并随机分配到4种日粮处理中的一种。处理方式包括无粗饲料的粗磨开食料（CON）或全混合日粮，其中全混合日粮分别含有基于干物质计7.5%的中等质量（MH）或低质量（LH）的蒂夫顿干草，或基于干物质计10%的玉米青贮（CS）。将粗蛋白、中性洗涤纤维、木质素和体外消化率等营养成分用作粗饲料质量标准。在出生后的前28天，所有犊牛每天两次各采食3升全脂牛奶，自由采食商业颗粒开食料，不提供粗饲料。此后，固体日粮改为各自的日粮处理方式。采集瘤胃样本以测定瘤胃pH值和挥发性脂肪酸（VFA）比例。犊牛在52至56日龄时逐渐断奶，断奶两周后，每组选取5头共20头犊牛进行屠宰。对胃肠道的解剖部位在有内容物和无内容物的情况下分别称重，并对瘤胃上皮进行组织学分析。与含粗饲料的日粮相比，CON日粮提高了总挥发性脂肪酸浓度。含粗饲料的日粮提高了瘤胃pH值、粪便pH值和瘤胃充盈度。然而，无论粗饲料来源如何，提供粗饲料均不影响空腹体重。此外，提供粗饲料增加了瘤胃乳头数量，但日粮对乳头的长度和宽度没有影响。结果表明，在高淀粉混合日粮中，无论质量如何，7.5%的蒂夫顿干草和10%的玉米青贮有利于瘤胃健康，能促进更大的瘤胃充盈度，且对最终体重无负面影响。
