Recent advances in ovulation synchronization and superovulation in ...

Abstracts. II International Symposium on Animal Biology of Reproduction, Nov. 19-22, 2008, São Paulo, SP, Brazil.
Influence of supplementation with protected unsaturated fat in pre-pubertal Nelore heifers
on the ovulation rate, blood glucose and cholesterol concentration during the rainy season
M.C.V. Miguel 1 , L.Z. Oliveira
1 , A.C.de Lucio 2 , D.R. Casagrande 3 , R.A. Reis 3 , G.P. Nogueira 4 ,
V.F.M.Hossepian de Lima 1
1 Dept of Preventive Veterinary Medicine and Animal Reproduction, FCAV/UNESP, Jaboticabal, SP, Brazil; 2 Dept of Animal
Improvement, FCAV/UNESP, Jaboticabal, SP; ³Dept of Animal Science, FCAV/UNESP, Jaboticabal, SP, Brazil; 4 Dept of
animal production and nutrition, FOA/UNESP, Araçatuba, SP, Brazil.
Introduction
Mammalian reproduction is influenced by many factors as species, breed, age, body condition score (BCS) and
nutrition. Among these, nutrition has an important role because of its direct effects on physiology and reproductive
performance. In bovine females, the amount of food intake or the food energy source affects many estrous cycle
characteristics, such as cycle length, follicular wave patterns and size of ovarian structures. Food restriction can
influence some of these variables because of the resulting reduction of blood glucose concentration. Also, the estrus
length and intensity can undergo alterations depending on the quality of the food taken in (1). Intake of diets
containing high levels of unsaturated fatty acids leads to an increase in blood cholesterol concentration and
positively modulates the ovarian physiology of cows (2). The aims of this work were to evaluate the ovulation rate
and the serum glucose and cholesterol concentrations in heifers receiving different types of diet.
Materials and Methods
Nelore heifers (n = 84) were maintained in Marandu pastures (Brachiaria brizantha cv.) since the age of eight
months. Heifers were divided to graze at two different grass heights (15 and 35 cm) and to receive three
supplementations strategies (two groups received Megalac-E® Protected Fat and the Control group received a
mineral supplement in the diet). Blood samples were collected by puncture of the jugular vein in intervals of 28 days
during the rainy season (January to May, 2008). Serum glucose and cholesterol levels were analyzed using
commercials kits (Sigma). The ovarian structures (follicles and corpus luteum) were examined by rectal palpation
for the detection of ovulations.
Results and Discussion
No cows grazing 15 cm grass in the Control Group ovulated (Table 1). In the remaining groups (supplemented with
Megalac-E® Protected Fat), CL were founded precociously (P < 0.05). Throughout the experimental period, glucose
levels were reduced (P < 0.05) in females maintained in the 15 cm pastures and remained constant in the female
maintained in the higher pastures (height of 35 cm). The glucose levels were not affected by the
supplementation (P > 0.05). The cholesterol levels remained constant in the control groups (142.2mg/dl in
15cm and 135.0 mg/dl in 35cm) but increased towards the end of the experimental period in the supplemented
groups (202.7 mg/dl in 15cm and 200.7 mg/dl in 35cm). Nevertheless no significant difference was found in the
cholesterol levels among the supplementation groups and the different heights of pasture (P > 0.05). The groups
supplemented with Megalac-E® Protected Fat demonstrated precocious CL presence. Therefore, it can be concluded
that supplementation is favorable to animal reproductive precocity.
Table 1. Corpus Luteum detection in the pre-pubertal Nelore heifers managed with different heights of pasture and
supplementation.
Supplementation Groups
Corpus Luteum (average± SD)
15 cm pasture height 35 cm pasture height
Mineral Salt (Control Group) 0.00 ± 0.00 b B a A
0.21 ± 0.43
Supplement 1 0.14 ± 0.36 a A a A
0.15 ± 0.38
Supplement 2 0.35 ± 0.50 a A a A
0.21 ± 0.43
Means with different superscripts in a row (minor letter) or in a column (capital letter) are different (P