Author ORCID Identifier

https://orcid.org/0009-0002-5083-8162

Date Available

6-25-2024

Year of Publication

2024

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College

Agriculture, Food and Environment

Department/School/Program

Animal and Food Sciences

Advisor

Dr. Surendranath P. Suman

Abstract

Consumers consider the surface color of fresh lamb as the indicator of freshness and wholesomeness, which affects their purchase decisions. The redox chemistry of myoglobin (Mb) determines the color of fresh lamb. Artificial raising on milk replacer (a pre-weaning strategy) as well as red clover supplementation are management strategies used in lamb production. This thesis focuses on the effects of artificial raising on milk replacer and red clover supplementation on the color and oxidative stability of fresh lamb.

In the first experiment, the effect of pre-weaning with milk replacer on the carcass attributes, color stability and lipid oxidation of lamb longissimus lumborum (LL) muscle were evaluated during refrigerated storage. Polypay ram lambs were subjected to artificial raising on milk replacer (n = 10) or conventional raising with ewes (n = 10). Lambs were weaned at 60-d and then were wither fed ad libitum high-forage (50:50 concentrate:forage ) or a high-concentrate (85:15 concentrate:forage) diet until reaching the target slaughter weight of 59 kg. Following harvest, fabricated 2.5-cm LL chops were placed on oxygen permeable polyvinyl chloride (PVC)-overwrap packaging and stored at refrigeration temperature (2°C) in darkness. Instrumental color, color stability (R630/580), pH, lipid oxidation, and metmyoglobin reducing activity of the chops were evaluated on 0, 3, and 6 days of storage. The carcass characteristics, surface redness (a* value), yellowness (b* value), hue angle, chroma, color stability (R630/580), pH, lipid oxidation, and metmyoglobin reducing activity (MRA) of LL chops were not affected (P > 0.05) by the pre-weaning management and finishing diet. During storage, lipid oxidation, yellowness (b* value), and hue angle of the chops increased (P < 0.05), whereas color stability (R630/580) and MRA decreased (P < 0.05) in both treatments. The findings indicated that feeding milk replacer can be successfully utilized as an artificial raising strategy in lamb production without compromising fresh meat color.

In the second experiment, the influence of red clover (Trifolium pratense L.) supplementation on the carcass characteristics, color stability, and lipid oxidation of lamb LL muscle were examined during 6 days of storage. Polypay ram lambs were blocked by body weight and sire and then randomly assigned to 4 treatments: 85:15 concentrate:roughage with orchardgrass (Dactylis glomerata L.) without red clover (control; n = 6); 2.5% red clover with 12.5% orchardgrass (n = 6), 5% red clover with 10% orchardgrass (n = 6), and 7.5% red clover with 7.5% orchardgrass (n = 6) during the finishing phase. The lambs were fed ad libitum until reaching the target slaughter weight of 59 kg. Following harvest, LL muscles were fabricated, and 2.5-cm thick LL chops were placed on oxygen-permeable PVC packaging and assigned to refrigerated storage in darkness. Instrumental color, color stability (R630/580), pH, lipid oxidation, MRA, and total color change (ΔE) were analyzed on 0, 3, and 6 days of storage. The hot carcass weight, cold carcass weight and lamb left shoulder increased in lambs supplemented with red clover diets (2.5% and 7.5%). Surface redness (a*), yellowness (b*), hue angle, chroma, color stability (R630/580), pH, lipid oxidation, and MRA were not affected (P > 0.05) by the red clover supplementation. During storage, meat pH, color stability (R630/580), redness (a*) and chroma decreased (P < 0.05), whereas the yellowness (b*), lipid oxidation, and hue angle increased (P < 0.05) in all samples. LL chops from red clover supplemented lambs (2.5%, 5%, and 7.5%) exhibited lower total color change (ΔE) than their control counterparts. These findings suggested that the supplementation of red clover can be a promising feeding strategy in lamb production without compromise of the fresh lamb color.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2024.251

Funding Information

This study was supported by the United States Department of Agriculture - Agricultural Research Service, National Program 101, Food Animal Production (ARS Project 5042-32630-003-00D) in 2022.

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