Dietary marine algae meal (schizochytrium sp.) for feedlot lambs: performance, digestibility and carcass and meat quality

Author(s)

Thiago Henrique Borghi

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2018-04-12.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2018-03-06
• Advisor: Américo Garcia da Silva Sobrinho

Abstract

This study was undertaken to evaluate the performance, nutrient digestibility, quantitative parameters of carcass, and qualitative and sensory parameters of meat in feedlot-finished lambs fed diets with increasing levels of marine algae meal inclusion. Thirty-two newly weaned 60-day-old uncastrated Ile de France lambs weighing 20.0 ± 0.2 kg body weight were used. The animals were housed in invidual pens and slaughtered at 35.0 ± 0.2 kg. The treatments were composed of four diets: D0- corn silage + concentrate without algae meal; D2- corn silage + concentrate + 2% algae meal; D4- corn silage + concentrate + 4% algae meal; and D6- corn silage + concentrate + 6% algae meal. The roughage:concentrate ratio was 40:60, and diets were formulated with similar protein (15%) and energy (3.3 Mcal digestible energy/kg DM) contents. The data were evaluated in a completely randomized experimental design, with four treatments and eight replications. The results were submitted to analysis of variance and regression. The algae meal contente were broken down into linear, quadratic and cubic effects. Marine algae meal levels influenced (P<0.05) nutrient intake, with a linear decrease seen in DM, OM, CP, NDF, ADF and GE; the opposite effect was found on EE, which increased linearly. Likewise, nutrient digestibility was influenced (P<0.05) by the algae meal levels, which linearly reduced the digestibilities of DM, OM, NDF, ADF, TC, and NFC. The digestibility of the EE fraction rose linearly (P<0.05), whereas that of CP responded (P<0.05) quadratically. Liver weight increased (P<0.05) linearly. Rumen papillary measurements in the lambs decreased (P<0.05) as the meal was included in the diet. In the performance trial, a linear increase (P<0.05) was observed for days in the feedlot, while dry matter intake and average daily weight gain decreased linearly. Feed conversion did not change (P>0.05). The yields of carcass and primal cuts, chilling losses, and longissimus muscle measurements did not differ (P>0.05). Likewise, no significant differences were observed for the lamb meat physicochemical traits. Sensory analysis revealed a linear (P<0.05) decrease in the attributes aroma, taste, and consumers’ purchase intention. Dietary inclusion of marine algae meal did not influence (P>0.05) the centesimal composition of lamb meat. The meat cholesterol content decreased linearly (P<0.05) and lipid oxidation responded in the opposite direction, increasing linearly. In the fatty acid profile, increasing linear (P<0.05) effects were found for the concentrations of 16:0, 17:0, 18:1 n-7, 18:2 c9t11, 20:5 n-3, and 22:6 n-3 fatty acids, while 18:0, 18:1 n-9, and 18:2 n-6 decreased linearly. Concentrations of MUFA and PUFA and MUFA:SFA and PUFA:SFA ratios had a quadratic response (P<0.05). The treatments elicited a linear decrease (P<0.05) in total n6 fatty acids, while fatty acids of the n-3 family and n-6:n-3 ratio responded quadratically. The desaturase-16 enzyme activity declined linearly (P<0.05). Elongase activity, atherogenicity and thrombogenicity indices, hyper- and hypo-cholesterolemic fatty acid concentrations, and h:H ratio responded quadratically (P<0.05). The marine algae meal did not show an interesting alternative, since consumption and the digestibility of the nutrients is impaired, leading to lower performance of the animals. The increase of palmitic acid in the lamb meat overlies all the benefits inherent to the n-3 family of fatty acids. (AU)

• FAPESP's process: 16/02311-1 - Dietary marine algae (Schizochytrium sp.) for feedlot lambs: performance, digestibility and carcass and meat quality
• Grantee: Thiago Henrique Borghi
• Support Opportunities: Scholarships in Brazil - Doctorate