Effect of dietary energy on seminal plasma insulin-like growth factor-I (IGF-I), serum IGF-I and testosterone levels, semen quality and fertility in adult rams.

The objective of the present study was to modulate seminal plasma insulin-like growth factor-I (IGF-I) by dietary energy and assess the relationship among testosterone and IGF-I levels, semen quality and fertility in adult rams. Twenty-four 1-yr old adult Nellore rams were equally divided into three groups (n = 8) and fed with three different concentrate mixtures formulated using conventional ingredients and finger millet (Eleucine corocana) straw to ensure rams received with similar amount of crude protein with three levels of energy. Rams in low-energy group were offered diets with 20% less energy than the control energy group (optimum energy, 100%, recommended energy level), whereas rams in high energy group were offered diets with 20% more energy than the optimum energy group. Semen was collected from rams 60 days after start of the experimental feeding. The percentages of progressive forward motility, functional membrane integrity and mitochondrial membrane potential of the spermatozoa were significantly (P < 0.05) higher in control and high energy groups as compared to low-energy group. Feeding of low-energy diet significantly (P < 0.05) decreased spermatozoa VSL, VCL and VAP when compared to control and high energy fed groups. The number of spermatozoa binding/oocyte was significantly (P < 0.05) higher in control (11.23 ± 0.20) and high energy (10.57 ± 0.19) groups as compared to the low energy (6.14 ± 0.01) group. The serum and seminal plasma IGF-I levels were significantly (P < 0.05) higher in control and high energy fed groups as compared to the low-energy group. The serum testosterone and cholesterol levels were significantly (P < 0.05) higher in the control group as compared to the low-energy group. The seminal plasma fructose levels in optimum energy fed animals were significantly (P < 0.05) higher as compared to other two groups. The seminal plasma IGF-I level had positive correlation with progressive forward motility (r = 0.7) and other velocity (linearity, r = 0.7; straightness, r = 0.7) parameters. The study suggested that the modulation of seminal plasma IGF-I levels by dietary energy is possible and the optimum level of seminal plasma IGF-I is necessary and sufficient to influence semen quality.

Selvaraju S ，Sivasubramani T ，Raghavendra BS ，Raju P ，Rao SB ，Dineshkumar D ，Ravindra JP ... -  《-》

Evaluation of maize grain and polyunsaturated fatty acid (PUFA) as energy sources for breeding rams based on hormonal, sperm functional parameters and fertility.

Selvaraju S ，Raju P ，Rao SB ，Raghavendra S ，Nandi S ，Dineshkumar D ，Thayakumar A ，Parthipan S ，Ravindra JP ... -  《-》

Influence of IGF-I on buffalo (Bubalus bubalis) spermatozoa motility, membrane integrity, lipid peroxidation and fructose uptake in vitro.

Selvaraju S ，Reddy IJ ，Nandi S ，Rao SB ，Ravindra JP ... -  《-》

Rams genetically superior for IGF-I do not exhibit improved male reproductive traits.

Insulin-like growth factors (IGFs) play an important role in regulating normal physiology, and may be involved in the control of reproduction. The aim of this study was to define the relationship between IGF-I concentrations and reproductive performance over the breeding and non-breeding seasons in lines of New Zealand Romney rams that had been selected for low and high blood serum IGF-I concentration. Yearling rams from two selection lines (13 from the high line and 19 from the low line) were examined in July (winter), September (autumn) and November (summer) 2006 and March (spring) 2007. Scrotal circumference including the inguinal skin was recorded. Semen was collected by electroejaculation on 4 occasions over a 12-month period. Semen was evaluated according to standard procedures (volume, motility, density and morphology). Samples were collected from four animals from each group for measurements of mRNA for IGF-I and the IGF type 1 receptor (IGF 1R) in the testis, and IGF-I, IGF 1R and the insulin receptor (IR) in the liver. Blood samples were collected via jugular venipuncture for the measurement of IGF-I, insulin and testosterone. The incidences of morphologically abnormal sperm cells, the scrotal circumference and sperm motility were higher in the breeding than in non-breeding season. Seasonal changes were found in the percentage of abnormal sperm, scrotal circumference, sperm motility and sperm density, but there were no differences between lines in any reproductive parameters. IGF-I mRNA levels were higher in the high than the low line in the liver but not in the testis, whereas the opposite was found for levels of IGF 1R mRNA. mRNA levels for the insulin receptor in the liver were higher in the high line. Plasma testosterone concentrations did not differ between lines, whereas the concentrations of IGF-I and insulin were higher in the high line. The results suggest that IGF-I may be locally produced in the liver and the testis, and that selection for high IGF-I may not be associated with improved reproductive performance in rams.

Park EK ，Chu JP ，Parkinson TJ ，Cockrem JF ，Han KS ，Blair HT ，Kim TY ，Yoon JT ，Lee YS ... -  《-》

Reproductive performance, blood testosterone, lipid peroxidation and seminal plasma biochemistry of rabbits as affected by feeding Acacia saligna under subtropical conditions.

Yousef MI 《FOOD AND CHEMICAL TOXICOLOGY》