Intake, nutrient digestibility, rumen parameters, growth rate, carcase characteristics and cannabinoid residues of sheep fed pelleted rations containing hemp (Cannabis sativa L.) stubble.

The feeding value and impact of hemp stubble in the diet of ruminants is unknown. Fifteen Merino castrated male sheep were maintained in individual pens and fed one of three pelletized experimental inclusion diets, as a 0% (Control), 28% (Hemp 1), and 56% (Hemp 2) pellet that delivered a diet meeting the nutrient requirements of the animals. Inclusion of hemp stubble had no effect (P > 0.05) on either DM intake, live weight gain or the feed to gain ratio but positively impacted (P < 0.05) on nutrient digestibility. Hemp stubble inclusion increased the concentration (but not molar proportions) of acetic and butyric acids and increased both the concentrations and molar proportions of iso-butyric, iso-valeric, hexanoic and heptanoic acids, possibly due to increased protein digestibility and/or changes in the composition of rumen cellulolytic bacteria. Tetrahydrocannabinolic acid (THCA) was the only cannabinoid found in plasma in the sheep fed the hemp-containing diets, and this was found at very low concentrations (<16 µg/L). The psychoactive cannabinoid delta-9-tetrahydrocannabinol (Δ 9-THC) was not detected in any plasma samples. THCA was detected in the liver of two sheep fed the Hemp 1 pellets and two sheep fed the Hemp 2 pellets. Cannabidiol (CBD) was detected in the liver of one sheep fed the Hemp 2 pellets (but no liver THCA was detected in this sheep). Δ 9-THC was detected in both the kidney fat and subcutaneous fat of all sheep fed hemp stubble, with the concentrations being higher (P < 0.05) in the sheep fed the Hemp 1 pellets. THCA was also detected in the subcutaneous fat of one of the sheep fed the Hemp 1 pellets. Four of the five sheep fed the Hemp 1 pellet and one of the five sheep fed Hemp 2 pellet had detectable levels of Δ 9-THC in the meat (loin). No other cannabinoids were detected in the meat. Current food standards regulations in Australia prohibit presence of any cannabinoid residues in commercial meat products; thus, determination of a withholding period is required to enable the safe feeding of hemp-stubble to sheep. Further research is also required to gain a greater understanding of the rumen metabolism of cannabinoids.

Transplacental transmission of Theileria orientalis occurs at a low rate in field-affected cattle: infection in utero does not appear to be a major cause of abortion.

BACKGROUND: Bovine theileriosis, caused by the haemoprotozoan Theileria orientalis, is an emerging disease in East Asia and Australasia. Previous studies have demonstrated transplacental transmission of various Theileria spp. but molecular confirmation of transplacental transmission of T. orientalis has never been confirmed in the field. In this study, cow-calf (< 48 h old) pairs were sampled across 3 herds; opportunistic samples from aborted foetuses or stillborn calves were also examined. Molecular (multiplex qPCR) and serological (ELISA) methods were used to determine infection prevalence and the presence of anti-Theileria antibodies in each herd. In addition, pregnant heifers and foetal calves were sampled at abattoir and tested for the presence of T. orientalis by qPCR. RESULTS: The qPCR results indicated that, even though there was a high prevalence of T. orientalis infection in cows, the rate of transplacental transmission to their calves was low, with only one newborn calf from one herd and one foetus from the abattoir testing positive for T. orientalis DNA. Five aborted foetuses and stillborn calves, 3 of which were derived from a herd experiencing a high number of clinical theileriosis cases at the time of sampling, all tested negative for T. orientalis by qPCR. This suggests that in utero infection of calves with T. orientalis may not be a major driver of abortions during theileriosis outbreaks. Temporal monitoring of 20 calves born to T. orientalis-positive mothers indicated that T. orientalis was detectable in most calves between 10 and 27 days post-partum, consistent with prior field studies on adult cattle introduced to Theileria-affected herds. There was a positive correlation between the ELISA ratio of newborn calves and their mothers within 48 h of calving; however, maternal antibodies were only detectable in some calves and only for 4-4.5 weeks post-partum. All calves displayed high parasite loads peaking at 4-8 weeks post-partum, with only some calves subsequently mounting a detectable adaptive antibody response. CONCLUSIONS: These findings indicate transplacental transmission of T. orientalis appears to play only a minor role in persistence of T. orientalis infection in the field; however calves are highly susceptible to developing high level T. orientalis infections at 4-8 weeks of age regardless of whether maternal antibodies are present post-partum.