Document Type

Thesis - Open Access

Award Date

2026

Degree Name

Master of Science (MS)

Department / School

Animal Science

First Advisor

Ana Clara B. Menezes

Abstract

Nutritional management and lactation performance are critical factors influencing productivity in cattle. This research includes two complementary studies. The first study was a meta-analysis to develop a lactation curve for Bos taurus cattle in North America using data from machine or hand milked cows. Data from 7 studies were used resulting in 1340 cow-day observations. Milk yield was analyzed by parity (primiparous or multiparous) and feeding management (non-nutrient restricted or nutrient restricted), revealing that primiparous cattle peaked earlier and at lower yields than multiparous cattle, and nutrient restriction reduced peak milk yield. Overall, Bos taurus cattle followed lactation trends similar to Bos indicus cattle, with peak milk occurring later. The second and third studies evaluated the effects of winter-feeding a limit fed high concentrate corn-based diet versus an ad libitum high forage hay-based diet on cotyledonary placental tissue, colostrum and milk yield and composition, immunoglobulins (Ig) in colostrum, hormonal and metabolic profile of beef cows and calves, dam dry matter and water intake, dam enteric methane (CH4) emissions, and cow-calf performance. Forty-six Angus and Angus-Simmental crossbred cows were blocked by age. Within block, cows were homogenously distributed by BW and breed and randomly assigned to two treatments: ad libitum feeding of a hay-based diet (HFOR; n = 23); or a corn-based diet limit-fed at 1.2% BW (HCON; n = 23). The HCON treatment increased gene expression in cotyledonary tissue related to immune function and energy metabolism, improved colostrum yield, milk fat yield, and energy-corrected milk, and reduced pre- and post-calving dry matter and water intake and enteric methane emissions. Additionally, the HCON cows spent less time eating and had fewer visits to the feed bunk in comparison to HFOR cows. The HCON cows weighed less than the HFOR cows for a majority of the feeding period, but experienced compensatory gain at the end of the feeding period to weigh the same as HFOR cows. There were no differences observed between treatments for calf performance. These findings support the use of a high concentrate corn-based diet as an alternative to improve lactation parameters and optimize efficiency in beef cow-calf systems.

Publisher

South Dakota State University

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Included in

Beef Science Commons

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Rights Statement

In Copyright