Gabriel Miranda Moreira, Gleidson Luz Aguiar, Javier Andrés Moreno Meneses, Karolina Batista Nascimento, German Dario Ramirez-Zamudio, Thais Correia Costa, Marcio de Souza Duarte, Daniel Rume Casagrande, Mateus Pies Gionbelli
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引用次数: 0
Abstract
This study aimed to quantify the effects of physiological status (PS) and potential interaction of this factor with days of pregnancy (DOP) on beef heifers' weight variation, intake, and digestion kinetics. Twelve rumen-cannulated zebu beef heifers (n = 7 pregnant; n = 5 non-pregnant) were used. Heifers were placed in individual pens and fed medium-quality corn silage plus a protein-based supplement. Heifers' body weight was assessed at the beginning and end of each collection period. The feed intake was measured daily. Target outcomes were evaluated at 107, 170, 208, 240, 267, and 286 days of pregnancy. The apparent total-tract digestibility was determined considering the fecal spot collection, during five days within each collection period. Omasal and ruminal digesta samples were collected at 107, 208, and 267 days of pregnancy for determination of partial digestibilities and diet component outflow. For these purposes, Co-EDTA and indigestible neutral detergent fiber (iNDF) were used as indicators. All data were analyzed using a mixed model framework, considering the PS and DOP as fixed effects and the animal as a random effect. Significant differences were declared when P ≤ 0.05. Pregnant heifers showed an increase in body reserves (+35 kg) from 107 to 240 days of pregnancy, but experienced a decrease in shrunk body weight (-36 kg) from 240 to 286 days of pregnancy. The intake of dry matter (DM), organic matter (OM), crude protein (CP), and ash- and protein-free neutral detergent fiber (apNDF) increased as pregnancy progressed (P < 0.04). The apparent total-tract digestibility of DM tended to be lower (P = 0.09), and the apparent total-tract digestibility of apNDF was reduced (P < 0.01) in pregnant heifers. The digestibility of CP was higher (P < 0.01) on days 267 and 286 in pregnant cows compared to non-pregnant heifers. The ruminal digestibility of OM tended to be lower (P = 0.09) in pregnant beef heifers, while the ruminal digestibility of apNDF was lower (P = 0.02) in pregnant heifers compared to non-pregnant ones. The ruminal pool of wet matter and DM was lower (P ≤ 0.01) in pregnant heifers at 267 days of pregnancy. In all periods, the outflow tended to be greater (P = 0.06) in pregnant heifers compared to non-pregnant heifers. Pregnant beef heifers exhibited a faster (P = 0.01) digesta passage rate during late gestation. In conclusion, late-gestating beef heifers are less efficient in extracting energy from feed compared to non-pregnant animals.
期刊介绍:
The Journal of Animal Science (JAS) is the premier journal for animal science and serves as the leading source of new knowledge and perspective in this area. JAS publishes more than 500 fully reviewed research articles, invited reviews, technical notes, and letters to the editor each year.
Articles published in JAS encompass a broad range of research topics in animal production and fundamental aspects of genetics, nutrition, physiology, and preparation and utilization of animal products. Articles typically report research with beef cattle, companion animals, goats, horses, pigs, and sheep; however, studies involving other farm animals, aquatic and wildlife species, and laboratory animal species that address fundamental questions related to livestock and companion animal biology will be considered for publication.