Reproductive parameters of Nelore males of low and high feed efficiency supplements with protected fatty acids in pasture

Author(s)

Guilherme Fazan Rossi

• Document type: Doctoral Thesis
• Press: Jaboticabal. 2017-06-23.
• Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
• Defense date: 2017-05-26
• Advisor: Gisele Zoccal Mingoti; Enilson Geraldo Ribeiro; Fábio Morato Monteiro; Flávia Fernanda Simili

Abstract

Diets enriched with sources of polyunsaturated fatty acids (PUFAs) for young bulls from puberty to sexual maturity may have a positive effect on reproductive performance. In addition, selecting young animals with better feed intake (low residual feed intake - RFI) is very important for breeding programs. Thus, the aim of this study was to evaluate the reproductive parameters of young Nelore bulls of low and high feed intake supplemented with PUFA in the pasture. The total of 48 young males were used with a 14.3±0.13 months of age and a weight of 389.5±5.43 kg. The experimental design were completely randomized in a factorial 2 x 2 (RFI x supplementation) being 24 animals high RFI with or without supplementation with PUFA and 24 animals low RFI with or without supplementation with PUFA. The diets were isoproteic. The supplementation period was from December to October and the animals were kept in Brachiaria brizantha cv. Marandu pasture in continuous stocking during the experimental period. The measurements of growth characteristics, feed intake, plasma concentrations of metabolites and hormones, andrological evaluation and testicular ultrasonography were performed every 28 days, from 14 to 24 months of age. Sperm cryopreservation was performed it the last collections, at which time the animals were 24 months old. After thawing, computer aided semen analysis (CASA), rapid thermoresistance sperm tests (TTR), integrity of the plasma membrane and acrosomal and in vitro embryo production (IVEP) were performed. The data were analyzed by the SAS procedure PROC MIXED. The low CAR bulls have had higher initial body weight (398.0±5.4) than high CAR (380.9±5.4) and maintained the difference throughout the experiment (P<0.05). The animals that received supplementation with PUFA had higher plasma concentrations of cholesterol, high density lipoprotein (HDL) and testosterone (161.5±3.2 ng/dL, 67.2±1.6 ng/dL e 12.2±0.6 ng/mL, respectively) in relation to treatments without PUFA (124.5±3.2 ng/dL, 57.9±1.6 ng/dL e 10.5±0.6 ng/mL, respectively) (P<0.05). No differences were observed between treatments for feed intake, testicular ecotexture, analysis of fresh semen and IVEP (P>0.05). However, sperm evaluation after thawing, the spermatic velocities (VAP - average path velocity, VSL - straight linear velocity and VCL - curvilinear velocity; μ / s) analyzed y CASA were hi her for bulls supplemented with PUFA (82.6±1.6, 68.6±1.2 e 132.0±3.2 para VAP, VSL e VCL, respectively) in relation for bulls without PUFA (76.2±1.6, 64.2±1.2 e 122.3±3.2; VAP, VSL e VCL, respectively) (P<0,05). Despite these differences in sperm velocity, coleterol and testosterone evaluations are needed in conjunction with other reproductive tests to determine the actual influence of PUFA on sperm quality. (AU)

• FAPESP's process: 13/13696-3 - REPRODUCTIVE PARAMETERS OF NELORE MALES OF LOW AND HIGH FEED EFFICIENCY SUPPLEMENTS WITH PROTECTED FATTY ACIDS IN PASTURE
• Grantee: Guilherme Fazan Rossi
• Support Opportunities: Scholarships in Brazil - Doctorate