Relationship between Serum L-Carnitine Levels and Sperm Parameters in Boars

This study evaluated the relationship between serum L-carnitine level and sperm parameters in young boars. Serum L-carnitine and semen characteristics were determined for 61 young Duroc boars between the ages of 590 and 630 days. Multiple linear regression analysis was performed to predict total and progressive motility and the total number of spermatozoa based on serum total L-carnitine and free L-carnitine levels. Total number of spermatozoa was not associated with basal serum L-carnitine levels. A regression equation was found in which both total L-carnitine levels and free L-carnitine levels were significant predictors of total and progressive motility (P 0.05). These results suggest that serum L-carnitine level is an important selection parameter for stock boars.

Methionine and Threonine Requirements of Dutch Rabbits Fed under a Cecotrophy Prevention Program

It is suggested that the difference in body size between domestic-type rabbits and small pet-type rabbits results in different nutrient requirements. The nutritional requirements of pet rabbits have been assessed, although such assessments require evaluation throughout the rabbit life span. The present study was conducted under a cecotrophy prevention program with young and adult rabbits. Six male Dutch rabbits were housed individually in a dormitory-type cage, and they were randomly fed graded levels of dietary methionine and threonine, at ratios of 4:0, 3:1, 2:2, 1:3, and 0:4 mixed with two types of feed, 4:0 and 0:4. Four days after switching diets and 4 hrs after starting morning feeding, approximately one milliliter of blood was collected from the vein of the ear. Free amino acid concentrations in the plasma were determined with a high-speed amino acid analyzer. Plasma concentrations of methionine and threonine compared to dietary methionine and threonine levels are shown in young rabbits. The plasma concentration of methionine remained constant at a low level and then increased linearly. The intersection was estimated as 0.16 g/d. In the same manner, the intersection of the plasma threonine value was estimated as 0.27 g/d. These values were calculated as 0.27% and 0.47% of the diets, respectively. In the case of adult rabbits, the baseline was not obtained for dietary methionine and threonine levels. The methionine requirement was estimated as 0.11 g/d. The threonine requirement was estimated as 0.22 g/d. These values were calculated as 0.15% and 0.30% of the diets, respectively. In comparison with young and adult rabbits, both methionine and threonine showed a low baseline level in young rabbits, while their variations in plasma levels of adult rabbits were not determined. The requirement of both amino acids in young rabbits is higher than that in adult rabbits. The dietary values of both amino acids in young rabbits were also higher than those in adult rabbits. Small pet-type adult rabbits required lower amino acid levels than domestic-type rabbits.

L-Carnitine Contents in the Tissues of Rabbits Fed Urea as an Alternative of Dietary Protein

The present study was aimed to observe the effects of urea ingestion, non-protein nitrogen, on the disorder of nitrogen metabolism with the L-carnitine contents using the blood, kidney, liver, and femoral muscle as markers. A total of 8 Japanese white rabbits were used in this experiment. They were fed a basal diet prepared for the control group and the nitrogen volume proportionated to one-third of CP 14%, was replaced with urea in the feed of the experimental group for 7 days. On the final day, the animals were fasted from the previous evening and sacrificed. Blood was collected into a test tube at the same time of the sacrifice and their heart, kidney, liver and femoral muscle were collected. The L-carnitine contents in each sample and the urea in the blood were determined. The results of the growth test showed that there was no significant difference. Furthermore, there was no significant difference in the contents of L-carnitine and urea in each sample. It was concluded that nitrogen replacement of the diet with urea, in the range of 1/3 of dietary protein, had neither effect on the maintenance of body weight nor nitrogen balance, including the de novo synthesis of L-carnitine.