Masters Theses

Date of Award

8-2024

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Elizabeth A. Eckelkamp

Committee Members

Kyle McLean, Katie Mason

Abstract

Dairy cattle often face negative energy balance around parturition. Without proper nutrition, periparturient diseases develop and negatively impact farm profitability due to treatment costs and reduced milk production. This study evaluates calcium-supplementing ration concentrates and cost-effective sorghum silage sources to maintain healthy, high-producing cows during the transition period and early lactation.

In an eight-month study, dietary impacts on dry matter intake (DMI), blood and urine metabolites, and milk yield and components were recorded for 31 multiparous and 9 primiparous Holstein cows. Data were collected from 21 treatment (CMA) and 19 control (CON) cows, balanced for parity and projected calving date. Total mixed rations were adjusted to partially replace calcium carbonate, magnesium oxide, and sodium bicarbonate with CMA.

The GLIMMIX procedure of SAS 9.4 (P ≤ 0.05) was used to analyze treatment effects, maximum ambient temperature humidity index, projected 305-day mature equivalent milk, and their two-way interactions. No significant impacts of treatment on blood or urine metabolite status, DMI, colostrum quality or quantity, body weight, milk, fat, or protein yield were found between treatment groups (P > 0.05). Under non-heat stress, CMA cows ate more than CON cows from 31 to 120 DIM (29 vs. 25.3 ± 0.7 kg/d; P < 0.01). Treatment cows maintained ECM efficiency in heat stress from 31 to 120 DIM (P = 0.01), unlike CON cows that decreased from non-heat stress to heat stress. However, treatment milk efficiency was decreased compared to CON under heat stress (1.6 vs. 1.8 ± 0.1; P < 0.01) and non-heat stress (1.6 vs. 2.0 ± 0.1; P < 0.01).

The nutritional content of male sterile brown midrib sorghum (BMR) and corn was evaluated using wet chemistry and near-infrared spectroscopy. Corn had higher crude protein concentration than BMR harvested at 8 wk post heading (P = 0.01) but was comparable to BMR harvested at 7 wk post heading. No significant differences in dry matter, acid detergent fiber, neutral detergent fiber, or starch concentration were observed among forage type (P > 0.05). Suggesting that BMR was a viable alternative forage, though protein supplementation adjustments may be needed.

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