Poisoning by Brachiaria spp. in various lamb breeds at increasing levels of supplementation during growth / Intoxicação por Brachiaria spp. em várias raças de cordeiros com incremento nos níveis de suplementação durante o crescimento

The study evaluate the frequency of poisoning by Brachiaria spp. at the rearing, growth and termination stages in various lamb breeds at increasing supplementation levels. Forty-five lambs were used in the growth phase in pastures of Brachiaria spp. with a history of having induced poisoning. The lambs were distributed in nutritional treatments: lambs receiving mineral supplementation (MS), energy/protein supplementation (EPS) at 0.8% of body weight (bw), EPS at 1.6% bw and EPS at 2.4% bw. The lambs were allotted two flocks (F1 and F2) of 21 and 24 lambs each. Clinical signs of poisoning were observed in all treatments. All MS lambs died. The frequency of poisoning were highest in the 0.8% EPS and 1.6% EPS treatments. All lambs in the 2.4% EPS treatment recovered. F1 lambs had a higher frequency of poisoning than F2 lambs regardless of nutritional treatment. Morbidity rates for the F1 and F2 lambs were 52.3 and 16.7%, respectively. Supplementation was not sufficient to decrease the frequency of poisoning in lambs at the termination stage, which was dependent on the genetic origin of the lambs. EPS of 2.4% bw treatment, was an efficient nutritional strategy to minimize the effects of poisoning in lambs fed on Brachiaria spp.(AU)

O objetivo deste estudo foi avaliar a frequência da intoxicação por Brachiaria spp. nas fases de recria, crescimento e terminação em várias raças de cordeiros em níveis crescentes de suplementação. Quarenta e cinco cordeiros foram utilizados na fase de crescimento em pastagens de Brachiaria spp. com história de intoxicação, distribuídos em diferents tratamentos nutricionais: cordeiros recebendo suplementação mineral (SM), suplementação energética/protéica (SEP) a 0,8% do peso vivo (pv), SEP a 1,6% pv e SEP a 2,4% pv. Vinte e um cordeiros vieram do lote F1 e 24 cordeiros foram do lote F2. Sinais clínicos de intoxicação foram observados em todos os tratamentos. Todos os cordeiros com MS morreram. As frequências de intoxicação foram maiores nos tratamentos com 0,8% e 1,6% de SEP. Todos os cordeiros no tratamento com 2,4% de SEP se recuperaram. Cordeiros F1 apresentaram maior frequência de intoxicação que os cordeiros F2, independentemente do tratamento nutricional. As taxas de morbidade para os cordeiros F1 e F2 foram de 52,3 e 16,7%, respectivamente. A suplementação não foi suficiente para diminuir a freqüência de intoxicação em cordeiros na fase de terminação, dependente da origem genética dos cordeiros. O SEP de 2,4% pv, no entanto, foi eficiente para minimizar os efeitos da intoxicação em cordeiros alimentados com Brachiaria spp.(AU)

Poisoning by Brachiaria brizantha in flocks of naïve and experienced sheep.

The aim of this work was to study the effects of protodioscin ingestion in two different flocks of sheep: a flock of 23 crossbreed Mato Grosso do Sul Native sheep raised on Brachiaria spp. pastures from birth (experienced flock) in the state of Mato Grosso do Sul; and another flock (naïve flock) of 18 crossbred Dorper × Santa Inês sheep raised in the state of Paraná in Paspalum notatum and Lolium multiflorum pastures. The two flocks grazed together in a Brachiaria brizantha pasture during a 140-day period in the rainy season. At the beginning of the experiment and every 14 days thereafter, blood samples were collected for determination of serum activities of gamma-glutamyl transferase (GGT) and aspartate aminotransferase (AST), and for determination of the icterus index. On the same days, samples of young, mature and old B. brizantha leaves were collected for protodioscin quantification. Naïve sheep were more susceptible to poisoning by B. brizantha than experienced sheep. Six sheep in the naïve flock were poisoned, and two of these died. Two sheep in the experienced flock were poisoned, and one of them died. The mean activities of serum GGT and AST were significantly higher in the naïve flock, also evidencing a higher susceptibility to the poison. These results suggest that flocks of sheep include animals with different degrees of resistance to Brachiaria spp. poisoning and that culling the susceptible animals may considerably increase of the resistance of the flock. The clinical signs and the lesions were similar to those previously reported. However, in sheep with black coats, the main clinical sign was weight loss without photosensitization-mediated dermatitis. One sheep from the experienced flock presented cirrhosis, with clinical signs of exercise intolerance. The protodioscin concentration (% DM) ranged from 0.87% to 2.58% (mean ± SD: 1.64 ± 0.58) in young leaves, 1.16%-2.53% (1.67 ± 0.44) in mature leaves and 0.98%-2.07% (1.52 ± 0.37) in old leaves. A negative relationship was found between saponin concentration and total cumulative precipitation.