The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behaviour and testosterone (T4) concentration in pelibuey rams subjected to different semen collection frequencies. eighteen intact males were assigned randomly to one of two semen collection frequencies: in the high rate (HR) treatment, two ejaculations per week were obtained from each ram; one ejaculation every two weeks was collected under the low rate (LR) treatment. All animals were housed individually in contiguous 5 m x 5 m wire mesh pens and evaluated over a 12-month period. At the beginning of the experiment rams were 20 months old and 40-50 kg in weight. All rams ejaculated and produced semen throughout the year. Semen volume, sperm per ejaculation, testicular circumference and testicular volume were significantly (p < 0.05) greater during short days in all rams, regardless of the semen collection frequency, with the exception of sperm concentration, for which no variation was found in hr individuals, and reaction time and T4 levels, for which no variation was found in IR males. Rams subjected to HR collection were more affected by the short-day photoperiod than rams collected twice per week, exhibiting greater reduction (p < 0.05) in time to achieve their first ejaculation and in sperm per ejaculation, as well as greater increases (p < 0.05) in T4 concentration than IR rams (14.65 +/- 1.22 vs 23.53 +/- 5.34 s, (3.37 +/- 0.17) x 10(9) vs (3.52 +/- 0.20) x10(9) sperm and 8.68 +/- 0.44 vs 6.85 +/- 0.74 ng/ml, respectively). It was concluded that: (a) the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year, and (b) seasonal variation within variables was affected differently between semen collection frequencies.

ABSTRACT:The purpose of this experiment was to describe early behavioural responses to illness in rabbits and their relation with physiological changes to improve early detection of infection by Taenia pisiformis in rabbits. Twenty adult female New Zealand rabbits were randomly allocated to 2 groups to determine whether changes in behaviour and some physiological parameters can be induced in rabbits after a T. pisiformis infection. Infected animals were orally inoculated with 3000 eggs of T. pisiformis, while controls received only saline solution. Behavioural activity was recorded daily from 19:00 to 21:00 h starting 2 d before infection. Mate choice and rank status were assessed, and blood samples were collected at −2, 7, 14 and 25 d post infection (dpi) for hematological and hepatic function determinations. All animals were observed for clinical signs every other day from the beginning of the experiment and euthanised 25 dpi after last sampling. Infected animals spent more (P<0.01) time lying stretched (3.78±1.77 vs. 0.77±0.03%) and less (P<0.01) time grooming (1.95±1.31 vs. 2.58±0.10%) and at the watering trough (1.20±1.13 vs. 3.35±0.02%) than controls. These differences were noticeable 6 dpi and remained until the end of the experiment. No changes (P>0.05) were observed in the time spent at the feeder, rank status or mate choice. Leukocyte and lymphocyte concentrations increased (P<0.05), while heterophil counts decreased in infected rabbits as the experiment progressed. Furthermore, infected animals had larger concentrations of alkaline phosphatase as soon as 7 dpi. No clinical signs of the disease were detected. Necropsy fi ndings corroborated hepatic lesions and presence of the parasite in all infected animals. It was concluded that an infection with 3000 eggs of T. pisiformis induced changes in behavioural and physiological parameters that may improve early detection of sick rabbits.

The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behavior and testosterone concentration (T4) in dominant and subordinate Pelibuey rams. Six groups of three animals were evaluated every 2 weeks over a 12 month period. Dominant (D), medium (M) and subordinate (S) animals in each group were identified through a food competition test every 15 days. All rams ejaculated and produced semen throughout the year. A linear hierarchy was clearly established and maintained during the year. S rams had lower levels (P < 0.05) of semen volume, sperm concentration and testicular volume than D rams, regardless of season. Scrotal circumference was not influenced (P > 0.05) by their social position. D rams were more affected by the photoperiod, decreasing (P < 0.05) reaction times, increasing (P < 0.05) T4 and producing more (P < 0.05) sperm per ejaculation than S rams during short days (14.65 ± 1.22 vs 26.92 ± 1.65 s; 8.68 ± 0.44 vs 7.37 ± 0.40 ng/mL and 3.37 ± 0.17 vs 2.04 ± 0.16 sperm/109, respectively). Semen volume and sperm concentration were significantly (P < 0.05) greater during short days in all rams, regardless of their social status, with the exception of sperm concentration in D rams where no variation was found. M rams displayed variable values in the range between the D and S rams. It was concluded that the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year and that seasonal variation within the variables affected the social ranks differently.

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