BackgroundThe purpose of the study was to determine if the effect of llama OIF on LH secretion is mediated by stimulation of the hypothalamus or pituitary gland.MethodsUsing a 2-by-2 factorial design to examine the effects of OIF vs GnRH with or without a GnRH antagonist, llamas with a growing ovarian follicle greater than or equal to 8 mm were assigned randomly to four groups (n = 7 per group) and a) pre-treated with 1.5 mg of GnRH antagonist (cetrorelix acetate) followed by 1 mg of purified llama OIF, b) pre-treated with 1.5 mg of cetrorelix followed by 50 micrograms of GnRH, c) pre-treated with a placebo (2 ml of saline) followed by 1 mg of purified llama OIF or d) pre-treated with a placebo (2 ml of saline) followed by 50 micrograms of GnRH. Pre-treatment with cetrorelix or saline was given as a single slow intravenous dose 2 hours before intramuscular administration of either GnRH or OIF. Blood samples for LH measurement were taken every 15 minutes from 1.5 hours before to 8 hours after treatment. The ovaries were examined by ultrasonography to detect ovulation and CL formation. Blood samples for progesterone measurement were taken every-other-day from Day 0 (day of treatment) to Day 16.ResultsOvulation rate was not different (P = 0.89) between placebo+GnRH (86%) and placebo+OIF groups (100%); however, no ovulations were detected in llamas pre-treated with cetrorelix. Plasma LH concentrations surged (P < 0.01) after treatment in both placebo+OIF and placebo+GnRH groups, but not in the cetrorelix groups. Maximum plasma LH concentrations and CL diameter profiles did not differ between the placebo-treated groups, but plasma progesterone concentrations were higher (P < 0.05), on days 6, 8 and 12 after treatment, in the OIF- vs GnRH-treated group.ConclusionCetrorelix (GnRH antagonist) inhibited the preovulatory LH surge induced by OIF in llamas suggesting that LH secretion is modulated by a direct or indirect effect of OIF on GnRH neurons in the hypothalamus.

The aim of the study was to relate some pre-slaughter handling factors for lambs in a slaughterhouse, with the presence of bruises and high muscle pH in carcasses. Stocking density, transport distance and time, and type of slaughter (Conventional or Kosher) were registered in a sample of 1150 lambs that corresponded to 23 loads originated from different farms (Tierra del Fuego, Chilean Patagonia), distance and time of transport to slaughterhouse. The presence and characteristics of bruises were randomly registered in 50 carcasses per load, and muscle pH measured in loin and leg at 24 h postmortem. Transport distance fluctuated between 50 and 190 km, transport time between 1.5 and 12 h and a mean stocking density of 164 ± 32 kg/m 2 for lambs with an average live weight of 31 ± 6 kg was recorded. Of all the carcasses 22.7% showed some degree of bruising and the loin was the most affected anatomical region, accounting for 47.1% of lesions. Transport time and live weight showed association (P < 0.05) with bruising, with the most exposed animals being the heavier lambs (>30 kg) and those travelling for more than 4 h. In the leg a pH < 5.8 was predominant, while the predominant range in the loin was 5.8 to 6.3. Transport time, presence and number of bruises were the factors that had a significant association (P < 0.05) with pH. Due to this association, both bruising and meat pH in lamb carcasses should be used at slaughter plants as indicators of meat quality and also of animal welfare.

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