• Asian-Australasian Journal of Animal Sciences
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• v.13 no.11
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• pp.1529-1535
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• 2000

The aim of the present study was to determine whether brain corticotropin-releasing factor (CRF) and a new peptide, urocortin (UCN) have a direct action in brain mechanisms controlling feed, water and salt intake in sheep. We gave a continuous intracerebroventricular (ICV) infusion of the peptide at a small dose of $5{\mu}g/0.2ml/hr$ for 98.5 hrs from day 1 to day 5 in sheep not exposed to stress. Feed and water intake during ICV infusion of CRF or UCN decreased significantly compared to those during artificial cerebrospinal fluid (CSF) infusion. NaCl intake during infusion of CRF or UCN was the same as that during CSF infusion. Mean carotid arterial blood pressure (MAP) and heart rate during ICV infusion of CRF or UCN were not significantly different from that during CSF infusion. On the other hand, the plasma glucose concentration during ICV infusion of CRF or UCN tended to be higher than that during CSF infusion. These observations indicate that decreased feed intake induced by CRF and UCN infusion is not mediated by the activation of both the pituitary-adrenal axis and the sympathetic nervous system. The results suggested that brain CRF and UCN act directly in brain mechanisms controlling ingestive behavior to decrease feed and water intake, but do not alter salt intake in sheep.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.2
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• pp.236-244
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• 2020

Objective: The objective of this study was to evaluate the effects of different levels of quantitative feed restriction on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance in F1 Holstein/Zebu cows during the middle third of their lactation. Methods: Sixty F1 Holstein/Zebu cows with 111.5±11.75 days of lactation and an initial body weight (BW) of 499±30 kg (mean±standard error of the mean) were used. The experimental design was completely randomized with the following diet levels of feed restriction: 3.39%, 2.75%, 2.50%, 2.25%, and 2.00% of BW, with 12 replications for each level. The experiment lasted for 63 days, of which each period lasted 21 days with the first 16 days for diet adaptation followed by 5 days for collection of data and samples. Results: For each 1% of BW diet restriction, there was a decrease in dry matter intake of 5.26 kg/d (p<0.01). There was no difference in daily milk production (p = 0.09) under the restriction levels of 3.39% to 2.0% of BW. When corrected for 3.5% fat, milk production declined (p = 0.05) 3.46 kg/d for each percentage unit of feed restriction. Conclusion: Restricting the feed supply for F1 Holstein/Zebu cows in the middle third of their lactation period altered nutrient intake, nitrogen balance and ingestive behavior but did not affect milk production or feed efficiency. However, considering the observed BW loss and decrease in milk production corrected for 3.5% fat, restriction of no less than 2.5% BW is recommended.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.3
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• pp.379-385
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• 2018

Objective: The study aimed to evaluate sugarcane bagasse as roughage in lactating cow on feed intake, digestibility, ingestive behavior, milk production and composition, and microbial protein synthesis. Methods: Ten Girolando cows at initial body weight of $450{\pm}25.6kg$ and at $143.7{\pm}30.7days$ in milk were assigned in two $5{\times}5$ Latin square designs. Five 21-day experimental periods were adopted ($1^{\circ}$ to 14-day: diets adaptation period; $15^{\circ}$ to 21-day: data collection and sampling period). The diets consisted of four different levels of sugarcane bagasse (45%, 50%, 55%, and 60%) and a control diet, commonly adopted in the region, based on spineless cactus (25% sugarcane bagasse), formulated to meet 12 kg/d milk yield. Results: The dry matter (DM), organic matter (OM), and total digestible nutrients intakes and DM and OM digestibilities observed for 45% and 50% bagasse inclusion were similar to control diet, while that 55% and 60% bagasse inclusion were lower. Cows fed control diet, and bagasse diets of 45%, and 50% levels had the nutritional requirements attended, that guaranteed 12 kg/d of milk yield. The crude protein intake and digestibility of cows fed 45%, 50%, and 55% of bagasse inclusion were similar to control diet. The neutral detergent fiber (NDF) intake and digestibility differ for all bagasse diets related to control diet, while the non-fiber carbohydrates intake and digestibility for cows fed 45% of bagasse were similar for control diet. The intakes and digestibilities of nutrients decreased linearly in function of bagasse inclusion; NDF and indigestible NDF intakes did not vary. The ruminating time, feeding and rumination efficiency, microbial protein synthesis and milk yield decreased linearly with sugarcane bagasse inclusion. Conclusion: Sugarcane bagasse decreases milk production; however, its inclusion level in between 45% to 50% associated to concentrate could replace diets based on spineless cactus for crossbred dairy cow's producing 12 kg/d of milk.

• Asian-Australasian Journal of Animal Sciences
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• v.32 no.9
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• pp.1373-1380
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• 2019

Objective: This study ascertained effects of cactus pear in association with different roughage in the diet of F1 Holstein/Zebu cows on intake, nutrient digestibility, nitrogen balance, ingestive behavior and performance. Methods: Eight cows with $72{\pm}11$ days of lactation were used. The experimental design was simultaneous in two $4{\times}4$ Latin squares. Four experimental diets were used: Diet 1, sorghum silage as exclusive roughage; Diet 2, sorghum silage associated with cactus pear in a proportion of 50% of the roughage (dry matter basis); Diet 3, elephant grass (Pennisetum purpureum cv. Roxo) as exclusive roughage; Diet 4, elephant grass associated with cactus pear in a proportion of 50% of the roughage. The roughage:concentrate ratio was 75:25. Results: Dry matter intake (p = 0.01) was higher with sorghum silage. There were differences in dry matter intake (p = 0.01), crude protein (p<0.01), ether extract (p = 0.01), non-fibrous carbohydrates (p<0.01) and total digestible nutrients (p = 0.01) among the diets. Cactus pear in the diet reduced water intake by 44.52% (p<0.01). The nitrogen balance was 59.71% and 27.49% lower in animals treated with exclusive sorghum silage and sorghum silage associated with cactus pear in relation to diets with elephant grass and elephant grass associated with cactus pear, respectively (p<0.01). The diets did not influence the milk production (p = 0.70), 3.5% fat corrected milk production (p = 0.72) or feed efficiency (p = 0.61). Conclusion: The association of cactus pear with sorghum or elephant grass silage does not alter milk production, reduces the intake of dry matter and water and improves the digestibility of nutrients.