Relationship between Prenatal Characteristics and Body Condition and Endocrine Profile in Rabbits

Abstract

This study evaluated the relationship between prenatal characteristics and body condition and endocrine profile. A total of 25 non-lactating multiparous females were used. Body condition, measured as body weight and perirenal fat thickness, non-esterified fatty acids (NEFA), leptin, progesterone and 17β-estradiol were recorded at mating and 12 d of gestation. Ovulation rate, number of foetuses, ovary and foetal weight, length and weight of uterine horn, available space per foetus and maternal and foetal placental morphometry were recorded at 12 d of gestation. Ovulation rate showed a positive linear relationship with number of foetuses, ovary weight and NEFA. A negative linear relationship between ovulation rate and perirenal fat thickness and leptin was obtained. Ovulation rate was maximum when body weight and 17β-estradiol were 4.4 kg and 22.7 pg/mL, respectively. Foetal weight showed a positive relationship with perirenal fat thickness and a negative relationship with leptin. An increase in progesterone and NEFA concentration was related to a positive linear increase in number of foetuses and in uterine horn weight. Space available per foetus was affected both by the number of vessels that reach the implantation site and by position of the foetus in the uterine horn. In conclusion, body condition during mating and early gestation should be maintained within an optimal range to ensure the best prenatal characteristics. While 17β-estradiol, NEFA and leptin affected the ovulation rate, progesterone and NEFA affected foetal development. The number of vessels that reach the implantation site determines early foetal survival.

Keywords: NEFA; estradiol; foetuses; leptin; ovulation rate; perirenal fat thickness; placenta; progesterone.

Figure 1

Regression equation (standard error between brackets) at mating for the relationship between: (a) ovulation rate and number of foetuses; (b) ovulation rate per ovary and its ovary weight; (c) body weight and ovulation rate; (d) perirenal fat thickness and ovulation rate.

Figure 2

Regression equation (standard error between brackets) at mating for the relationship between ovulation rate: (a) NEFA; (b) 17β-estradiol; (c) leptin.

Figure 3

Regression equation (standard error between brackets) at 12 d of gestation for the relationship between: (a) perirenal fat thickness and total foetal weight; (b) leptin and total foetal weight; (c) progesterone and total foetal placenta weight; (d) progesterone and total maternal placenta weight.

Figure 3

Regression equation (standard error between brackets) at 12 d of gestation for the relationship between: (a) perirenal fat thickness and total foetal weight; (b) leptin and total foetal weight; (c) progesterone and total foetal placenta weight; (d) progesterone and total maternal placenta weight.

Figure 4

Regression equation (standard error between brackets) at 12 d of gestation for the relationship between progesterone and: (a) number of foetuses; (b) uterine weight; (c) uterine length.

Figure 5

Regression equation (standard error between brackets) at 12 d of gestation for the relationship between NEFA and: (a) uterine weight; (b) number of foetuses; (c) progesterone.

Figure 6

Regression equation (standard error between brackets) at 12 d of gestation for the relationship between number of foetuses per uterine horn and: (a) tract weight; (b) tract length.

Figure 7

Regression equation (standard error between brackets) at 12 d of gestation for the relationship between number of foetuses per uterine horn and: (a) maternal placenta length; (b) maternal placenta area; (c) available space per foetus.