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Animals 2018, 8(8), 133; https://doi.org/10.3390/ani8080133

Associations of Blood Analysis with Feed Efficiency and Developmental Stage in Grass-Fed Beef Heifers

1
Departamento de Zootecnia, Universidade de São Paulo, Pirassununga 13635-900, Brazil
2
AgSights, Elora, ON N0B 1S0, Canada
3
Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada
4
Department of Animal Biosciences, University of Guelph, Guelph, ON N1G 2W1, Canada
5
Department of Animal Science and Aquaculture, Dalhousie University, Truro, NS B2N 5E3, Canada
6
Animal Production, Welfare and Veterinary Sciences Department, Harper Adams University, Newport TF10 8NB, United Kingdom
*
Author to whom correspondence should be addressed.
Received: 11 June 2018 / Revised: 30 July 2018 / Accepted: 31 July 2018 / Published: 2 August 2018
(This article belongs to the Section Farm Animals)
Full-Text   |   PDF [586 KB, uploaded 2 August 2018]   |  

Simple Summary

Individual cattle of identical developmental stage vary in their efficiency of feed utilization to achieve a similar productive performance in terms of growth rate and body composition upon accounting for breed, age and gestation stage. Technical issues to measure individual feed intake on the farm limits the identification of feed-efficient cattle. This creates a demand for indirect approaches to infer feed efficiency, such as blood parameters. Our study revealed differences in blood parameters when comparing grass-fed heifers classified as either efficient or inefficient. These differences were also influenced by the developmental stage of the heifers; some blood analytes had distinct relevance to infer about feed efficiency when comparing younger non-pregnant heifers with older and pregnant heifers. In general, improved feed efficiency seems to relate to a lower oxygen carrying capacity. We also provide evidence of associations between indicators of the immune system, blood enzymes and ions and feed efficiency. Additionally, blood analysis presented metabolic differences between non-pregnant heifers with older and pregnant heifers. Blood analysis as a practical measure for feed efficiency has relevance in the nutritional management and genetic improvement of beef cattle, which will contribute to the broad sustainability of beef farming.

Abstract

Proxies for feed efficiency, such as blood-based indicators, applicable across heifers varying in genetic makeup and developmental state are needed. Assessments of blood analytes and performance were made in heifer calves and pregnant heifers. Residual feed intake, a measure of feed efficiency, was used to categorize each population of heifers as either efficient or inefficient. Efficient heifer calves had lower mean cell hemoglobin, greater lymphocyte count, and fewer segmented neutrophils at the end of the test compared to inefficient calves. Efficient pregnant heifers had greater counts of lymphocytes with fewer segmented neutrophils at the end than inefficient pregnant heifers. Efficient heifer calves exhibited higher specific immunoglobulin M than inefficient calves. Throughout the test, efficient heifer calves had elevated potassium and phosphorus, and reduced alkaline phosphatase (ALP) compared to inefficient heifers. Efficient pregnant heifers showed greater ALP, non-esterified fatty acids and creatinine, but lower cholesterol and globulin than inefficient pregnant heifers. Levels of red and white blood cells, creatine kinase, cholesterol, glucose, potassium and phosphorus were higher in heifer calves compared with pregnant heifers. There is potential for blood analytes as proxies for feed efficiency; however, it is necessary to consider the inherent associations with feed efficiency and heifers’ developmental stage. View Full-Text
Keywords: alkaline phosphatase; biomarker; hemoglobin; immunoglobulin; leukocyte; physiology indicator trait; potassium; pregnancy; residual feed intake; triiodothyronine alkaline phosphatase; biomarker; hemoglobin; immunoglobulin; leukocyte; physiology indicator trait; potassium; pregnancy; residual feed intake; triiodothyronine
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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MDPI and ACS Style

Cônsolo, N.R.B.; Munro, J.C.; Bourgon, S.L.; Karrow, N.A.; Fredeen, A.H.; Martell, J.E.; Montanholi, Y.R. Associations of Blood Analysis with Feed Efficiency and Developmental Stage in Grass-Fed Beef Heifers. Animals 2018, 8, 133.

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