Document Type

Thesis - Open Access

Award Date

2016

Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

David Casper

Keywords

cobalt lactate, essential oils, robotic milker, milk composition, nutrient digestibility

Abstract

The objective of this study was to determine if the inclusion of a blend of essential oils and cobalt lactate (EOC) in the diet of lactating dairy cows could result in improved nutrient utilization and lactational performance in addition to assessing the application of EOC to control feed mycotoxins and spoilage. The trial was conducted in two experimental periods (Phase 1 (P1) and Phase 2 (P2)) on a commercial dairy in southwest Minnesota equipped with two robotic milking units. Phases 1 and 2 were cross over design trials with two pens. Cows were housed in two freestall pens (57 ± 2 cows and 59 ± 3 cows for treatment (EOC) and Control pens, respectively) and were evaluated for cow parity (2.65 ± 1.52 and 2.33 ± 1.20), days in milk (DIM) (184 ± 103 and 154 ± 94.2), and milk production (35.4 ± 11.3 kg/d and 36.9 ± 11.3 kg/d) prior to study initiation and assignment to EOC or Control treatments. Each Phase included 14 d for dietary adaptation followed by 9 wk for data collection. Cows were fed a total mixed ration (TMR) with no treatment (Control) or 0.23 kg/hd/d of a soy hull carrier containing a proprietary blend of EOC to be fed at a rate of 28 g/hd/d. Daily milk production, management level milk (MLM), 3.5% fat corrected milk (FCM), and energy corrected milk (ECM) were similar (P > 0.10) for cows fed EOC and Control. Milk fat percentage and yield (kg) and protein percentage and yield (kg) were similar (P > 0.10) for cows fed EOC and Control. Milk fat percentage and yield (kg) measured by the Dairy Herd Improvement Association (DHIA) were significantly greater (P < 0.05) for cows fed EOC compared to cows fed Control for Phases 2 and 1 respectively. Both protein and lactose percentage and yield (kg) measured by DHIA were similar (P > 0.10) for cows fed EOC and Control. Milk urea nitrogen (MUN) was significantly lower (P < 0.05) for cows fed EOC than cows fed Control during P1 (P < 0.01), but was similar during P2 (P > 0.10). Somatic cell counts (SCC) were similar (P > 0.10) for cows receiving EOC and Control diets. Dry matter intake (DMI) was greater (P < 0.05) for cows fed EOC compared to cows fed Control during P1 but was similar (P > 0.10) during P2. Body weights were greater (P < 0.01) for cows fed EOC compared to cows fed Control during P1, however the opposite was true for P2 during which body weights were lower (P < 0.01) for cows fed EOC compared to cows fed Control. Body condition scores (BCS) were similar (P > 0.10) for cows receiving EOC and Control diets during both Phases. Body surface temperatures were similar (P > 0.10) between pens during both Phases. When evaluating dry matter (DM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and starch digestibility percentages during each phase, there were no differences between cows fed EOC and cows fed Control (P > 0.10), however a numeric advantage for cows fed EOC was observed. Mycotoxins detected in TMR composites from P1 and P2 were similar (P > 0.10). The time until a 2°C rise in temperature (aerobic stability of TMR) was numerically greater, but was not significant (P > 0.10) for TMR containing EOC compared to untreated TMR. Fecal composites from cows receiving EOC were lower (P < 0.05) in normal microbiota compared to cows receiving Control diet. Streptococcus sp. were lower (P < 0.05) during P1 for cows receiving EOC compared to cows receiving Control diet, but the measurement of Streptococcus sp. was similar (P > 0.10) during P2. Feeding EOC to lactating dairy cows appears to influence milk composition and nutrient digestibility, and may improve the aerobic stability of feed at the bunk.

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds.
Essences and essential oils.
Cobalt in animal nutrition.
Lactation.
Milk -- Composition.

Description

Includes bibliographical references (pages 48-59)

Format

application/pdf

Number of Pages

69

Publisher

South Dakota State University

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Rights Statement

In Copyright