Effects of castration age, protein level and lysine/methionine ratio in the diet on colour, lipid oxidation and meat acceptability of intensively reared Friesian steers

Abstract

A total of 64 intensively reared Friesian steers were used in a 2 × 2 × 2 design to study the effects of age of castration (15 days old v. 5 months old), dietary protein level (14.6% v. 16.8%; DM basis) and lysine/methionine (lys/met) ratio (3.0 v. 3.4) on meat quality. The lys/met ratio of 3.0 was reached with supplementation of protected methionine. Animals were slaughtered at a live weight of 443.5 ± 26.2 kg at around 12 months of age. Colour and lipid oxidation were measured in the longissimus thoracis muscle throughout the 14 days of display under modified atmospheric and commercial display conditions. A panel of 17 consumers assessed daily the visual acceptability of the meat on display. A consumer acceptability eating test was also performed with 120 consumers in meat aged for 7 days under vacuum conditions. Lipid oxidation was not influenced by castration age and the protein level in the diet. Castration age did not affect meat colour, but meat from the low protein level diet and the low lys/met ratio showed higher redness (a*) from 3 days of display onwards. Nevertheless, from 6 days onwards, consumer visual acceptability was below the level of acceptance in all treatments, and even from 5 days onwards in those animals that underwent early castration and were fed either a high protein diet or a combination diet low in protein content and high in lys/met ratio. The best accepted treatments throughout the display period were those from late castrated animals fed a low protein diet, probably related to other visual aspects. However, the best accepted meat after consumption was that from late castrated animals fed high protein and high lys/met. The addition of protected methionine to reach lys/met levels of 3.0 did not improve beef acceptability, with the high protein diet being preferred by consumers in terms of palatability in late castrated animals.

Effects of cottonseed hull levels in the diet and ageing time on visual and sensory meat acceptability from young bulls finished in feedlot

“…Each day, progressively, appraisers evaluated steaks with a significantly lower score, except for CH27 and CH33 diets, with values from the 2 nd day of display not differing from the 1 st day. Thus, exposure time reduced shelf life of meat as was previously observed Prado et al, 2015). The gradual decline in visual appraisal was expected because oxidative processes are a natural cause of meat deterioration, which is particularly relevant for meat from concentrate-fed animals, because of the lower vitamin E content in non-forage diets.…”

<b>Carcass characteristics and sensorial evaluation of meat from Nellore steers and crossbred Angus vs. Nellore bulls

“…The TBARS values ranged from 0.134 to 0.563 for Nellore steers and from 0.1733 to 0.5444 mg of MDA kg -1 of meat for Angus vs. Nellore bulls from day 1 to day 14, respectively. In general, lipid oxidation increases with ageing time (Prado et al, 2015). In any case, the MDA levels after 14 days of aging were below (0.55 of MDA kg -1 of meat) the threshold for acceptability in beef (Campo, et al, 2006).…”

“…Nellore steers presented L* meat value close to 39.1 points, while the L* meat value of Angus vs. Nellore bulls increased from 37.6 to 41.9 points during the ageing period, characterising an evolution from a darker to a lighter meat. For meat from Nellore steers, the L* value increased from day 1 to day 7 of the ageing period (37.1 to 41.6 points), a phenomenon that has been observed in beef steaks that were displayed under high levels of oxygen (Prado et al, 2015). Chemical changes in myoglobin did not influence L* meat values (McKenna, Mies, Baird, Pfeiffer, Ellebracht et al, 2005), but the protein structures that changed with ageing due to proteolysis-influenced lightness (Renerre, 1981).…”

Fundamentals and applications of forensic veterinary medicine in the welfare of dairy cattle: Review

“…Esta técnica consiste na compressão e esmagamento dos cordões espermáticos com interrupção sanguínea e consequente atrofia dos testículos. No entanto, a utilização do burdizzo é um procedimento de castração que afeta o bem-estar animal (King et al, 1991, Melches et al, 2007, sendo necessária a aplicação prévia de anestesia local para minimizar a dor (Lomax & Windsor, 2013, Prado et al, 2015. Estudos demonstram benefícios do uso de anestésicos e analgésicos na descorna de bezerros; apesar disso este procedimento vem sendo realizado rotineiramente sem aplicação prévia destes fármacos em vários países (Vickers …”