نوع مقاله : مقاله پژوهشی
عنوان مقاله English
نویسندگان English
Introduction: The long-term sustainability and profitability of dairy farms largely depend on the success of calf and heifer rearing programs. Nutrition is one of the most important pillars of animal husbandry and a key economic tool for optimizing production systems. Forage consumption by calves promotes rumen muscular development, stimulates rumination, and increases saliva secretion. Non-forage fiber sources, which are rich in cell wall components, can be considered alternatives to forages depending on their cost and availability. Utilizing non-forage fiber sources can help meet the nutritional needs of livestock while also reducing feed costs and maintaining rumen health. The aim of this study was to investigate the effects of non-forage fiber sources, including wheat bran and sugar beet pulp, in a starter diet on the performance, rumen fermentation, and blood parameters of Holstein heifer calves. This study may contribute to a better understanding of the role of non-forage fiber sources in improving calf health and performance and provide practical insights for optimizing nutritional strategies in dairy production systems.
Materials and Methods: The experiment was conducted using 24 Holstein heifer calves with an initial body weight of 37 ± 2 kg in a completely randomized design for a period of 90 days. The experimental diets included: (1) a barley-based starter, (2) a starter containing 15% wheat bran (DM basis) replacing barley, and (3) a starter containing 13.5% sugar beet pulp (DM basis) as a partial replacement for barley.The diets were identical in terms of energy content and crude protein content. Daily feed intake was measured and changes in calf weight were examined. Calves were weighed regularly every 15 days until the end of the experimental period. Blood samples were taken three hours after feed consumption from the jugular vein at ages 30, 60, and 90 days. Rumen fluid samples were collected three hours post-feeding using an esophageal tube at the end of the study (90 days), and urine and fecal pH were measured at the end of the study. Fecal consistency was evaluated daily throughout the experiment using a scoring scale from 1 to 5. Weaning age was recorded as an indicator of treatment performance and was defined as the age at which starter intake reached 900 g per day. Rumination was visually assessed, and the onset of rumination was defined as the age at which each calf was observed ruminating for three consecutive days; this age was recorded at the end of the third day.
Results and Discussion: The results indicated that calves fed wheat bran had higher average daily feed intake and daily weight gain compared with those fed sugar beet pulp. Incorporating non-forage fiber sources with highly digestible fiber in the diet leads to improvements in intake, health, and productivity. Previous studies on sugar beet pulp have reported both positive and negative effects on dry matter intake and performance in cattle and sheep. The rumen pH was influenced by the experimental treatments, with calves fed wheat bran exhibiting a higher rumen pH compared to the other treatments. Fiber consumption stimulated rumination and increased saliva secretion, which helped maintain a higher rumen pH.The treatments did not significantly affect the ruminal ammonia nitrogen concentration in the rumen fluid. The concentrations of triglycerides and VLDL were significantly lower (P < 0.05) in calves fed the wheat bran diet compared with the other treatments. were lower in calves fed the wheat bran diet compared with the other treatments.An increased level of fiber in the diet reduces fat digestion, as these fibers form complexes with bile salts, disrupting the VLDL reabsorption cycle, which consequently lowers VLDL levels in the blood. The lower triglyceride concentration in calves fed wheat bran during the post-weaning period compared to those fed sugar beet pulp may be attributed to higher starter intake during this period. The differences in final weight among the experimental treatments were significant (P < 0.05), with calves fed the barley-based starter showing the highest final weight.The differences in final weight among the experimental treatments were significant. Although there was no significant difference in total feed intake and feed efficiency among the treatments, the experimental diet containing sugar beet pulp resulted in a significant reduction in final weight compared to the starter diet containing barley.
Conclusion: The results of this study indicate that the inclusion of wheat bran as a non forage fiber source in the starter diet has beneficial effects on the health parameters of Holstein heifer calves compared with sugar beet pulp. These effects include higher feed intake, greater average daily gain compared with calves fed the sugar beet pulp diet, and improvements in ruminal pH as well as blood metabolites such as triglycerides and very low density lipoproteins (VLDL).
کلیدواژهها English
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