Pre- and post-cryopreservation semen viability in bulls supplemented with protected fat and/or antioxidants

Author(s)

Monique Mendes Guardieiro

• Document type: Doctoral Thesis
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2013-06-27

Examining board members

Roberto Sartori Filho; Margot Alves Nunes Dode; Carlos Frederico Martins; Leandro Rodello; Ivanete Susin

• Advisor: Roberto Sartori Filho

Abstract

Cryopreservation of semen is of fundamental importance to the expansion of reproductive techniques such as artificial insemination, embryo transfer and in vitro fertilization, however, it is responsible for the oxidative stress of the sperm cell. To enhance cell survival after freezing, the plasma membrane has to have sufficient fluidity that is guaranteed by polyunsaturated fatty acids and antioxidant defense to protect against lipid peroxidation. In order to make the sperm more resistant to cryopreservation, 48 Nelore bulls were confined (three animals per pen) and assigned to four treatments according to the addition of rumen protected fat and/or antioxidants to the diet. During 30 days, all bulls were fed the same adaptation diet (sugar cane bagasse, citrus pulp, corn gluten meal, urea and mineral salt). Thereafter, for 75 days, the same diet was offered, differing in the addition of: F) fat protected from rumen degradation (rich in linoleic acid; Megalac-E®, 1.5% DM, n = 12); A) Antioxidant (a source of vitamin C and selenium, EconomasE®, 3g/head/day, n = 12); FA) Megalac-E® and EconomasE ® (n = 12); or C) control group (n = 12). Semen collection and freezing were performed seven times: 0, 15, 30, 45, 55, 65 and 75 days of offering experimental diet period. Data were analyzed by repeated measures of GLIMMIX of SAS. Body weight and scrotal circumference did not differ between treatments (P = 0.37). The glutathione peroxidase activity in blood and seminal plasma was higher for diets containing antioxidants, especially at 75 days. The volume, mass motility, vigor, numbers of agglutinated spermatozoa in fresh semen were similar between groups. However, fat-containing diets reduced the total number of sperm (P = 0.07) and the percentage of normal spermatozoa (P = 0.09). Lipid peroxidation and the kinetics of thawed sperm were similar among diets. Moreover, diets not containing fat increased the percentage of intact sperm plasma membrane (PM) and unreacted acrosomal membrane (62.2 ± 2.87 vs 53.3 ± 2.87%, P < 0.05). In addition, diets without antioxidants caused an increase in the number of sperm cells with damaged PM and with Induction of sperm acrosome reaction. After 65 days of supplementation, sperm of bulls fed diets with fat had higher stability of the PM, compared to other treatments (60.4 ± 2.62 vs. 52.7 ± 2.62%, P = 0.05), however there was an increase the number of dead sperm (P = 0.10). The mitochondrial potential of spermatozoa was not affected by treatments. It is concluded that despite tha fact that the pre-freezing sperm viability was not affected by the experimental diets, beneficial effect to the sperm cells after cryopreservation was found when bulls were supplemented with diets containing antioxidants, compared to diets containing fat. (AU)

• FAPESP's process: 10/00586-7 - Pre and post cryopreservation viability of semen from bulls supplemented with rumen-protected fat and/or vitamin C and selenium
• Grantee: Monique Mendes Guardieiro
• Support Opportunities: Scholarships in Brazil - Doctorate