1. Prepartum and postpartum supplementation for grazing beef heifers on metabolic response and ovarian morphometry.
- Author
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Sánchez Beltrán, Bryan S. and Sotelo Moreno, Deilen P.
- Subjects
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HEIFERS , *GRAZING , *FATTY acids , *ANALYSIS of variance , *COWS - Abstract
Introduction: Nutrition and reproduction are fundamental but often neglected aspects in beef heifers, which exhibit a high degree of interaction associated with reproductive stress and high nutrient demand. This contributes to reproductive inefficiency in primiparous cows. Objective: To evaluate the effect of prepartum and postpartum supplementation on metabolic response and ovarian morphometry in grazing beef heifers. Methods: Twenty-eight Nelore heifers with 5.4±0.5 months of gestation, 459.7±6.8 kg, and 5.8±0.10 body condition score (Scale 1-9), respectively, were used. The experiment lasted 210 days and was conducted according to a completely randomized design with four treatments. The treatments were: 0.0, 0.4, 0.8, and 1.2 kg/animal/day of a protein supplement with 25% crude protein. All animals received ad libitum mineralized salt and had free access to water. Blood samples were collected 15 days before the expected calving date (-15), and 30 (+30) and 60 (+60) days postpartum to quantify serum urea nitrogen (SUN), non-esterified fatty acids (NEFAs), glucose, total proteins, globulins, triglycerides, and progesterone concentrations. Additionally, on days 30, 45, 60, and 75 postpartum, ovarian (diameter, circumference, and follicle number) and follicular (diameter and volume) measurements were taken from all animals via ultrasonography (Mindray DP-1100 Plus/DP-2200; 5 MHz linear probe). The results were subjected to analysis of variance and decomposed through orthogonal contrasts. Differences were considered significant at P<0.05. Results and Discussion: There were no effects (P>0.05) of supplement amounts on the diameter, circumference, and number of follicles present in each ovary, nor on the diameter or volume of the largest and second-largest follicle. Supplement amounts increased (P<0.05) blood concentrations of SUN and total proteins, with higher concentrations observed in cows receiving a greater amount of supplement. However, no treatment effect (P>0.05) was observed on serum levels of NEFAs, glucose, triglycerides, globulins, and progesterone. Conclusion: Offering a maximum of 1.2 kg/day of protein supplement to grazing beef heifers during prepartum and postpartum does not improve the energetic status or ovarian morphometry. [ABSTRACT FROM AUTHOR]
- Published
- 2024