Efectos de altos niveles de proteína en el último tercio de la gestación sobre el crecimiento postnatal de la progenie en bovinos para carne

Un bajo nivel nutricional preparto de la vaca de cría, se ha relacionado con menor productividad en la progenie a través del mecanismo de programación fetal. El exceso de proteína en la gestación tardía sobre este mecanismo es aún, poco estudiado. Esta situación puede observarse en sistemas dedicados a la venta de material genético (cabañas núcleo o multiplicadores). El objetivo del trabajo fue evaluar el efecto de una dieta pastoril de elevado nivel proteico (59 % por encima de los requerimientos) durante el último tercio de la gestación sobre el crecimiento de la progenie. Se utilizaron 16 hembras preñadas multíparas Aberdeen Angus alimentadas con diferentes niveles proteicos durante el último tercio de la gestación: uno sobre una pastura degradada compuesta principalmente por mío­mío (Baccharis coridifolia) y carqueja (Baccharis articulata), espartillo (Spartina sp.), pasto alambre (Sporobolus sp.), flechilla (Stipa sp) y cola de zorro (Setaria leucopila) y el otro sobre triticale (Tritico secale). La Proteína Bruta (PB) fue de (PB 13.92 % y 18.2 % respectivamente y el % de Digestibilidad in vitro fue de 65.5 % y 68.7 %). Los aportes de PB fueron 10 % y 59 % superiores a los requerimientos diarios, respectivamente. Se empleó un diseño experimental completamente aleatorizado con dos repeticiones y se asignaron al azar 8 animales a cada tratamiento. Se evaluó peso al nacer, peso a los 205 días, aumento diario de peso vivo predestete y peso al año. Mayores aportes de proteína afectaron negativamente el potencial de crecimiento (p < 0.05), sin afectar el peso al nacer. Los altos niveles de proteína bruta pudieron generar mayor demanda metabólica sobre la vaca gestante por efecto de la ureagénesis excesiva, que compite con otros procesos metabólicos por energía metabólica y diferentes metabolitos, entre ellos la metionina, aminoácido asociado al mecanismo de programación fetal.

Acute lead arsenate poisoning in beef cattle in Uruguay

We describe and illustrate lesions in an outbreak of lead arsenate poisoning in beef cattle that ingested pesticide residues stored in an abandoned building of a former orange orchard. Of 70 exposed cattle, 14 had diarrhea, paresis, ataxia, recumbency, and/or seizures. Ten of the affected animals died after a clinical course of 12–18 h. Pathologic findings in 3 steers included extensive necrohemorrhagic, ulcerative rumenitis, omasitis, and abomasitis; lymphocytolysis in lymphoid organs; and nephrosis. Hepatic arsenic and lead levels in cases 1–3 were 20, 24, and 31 ppm, and 8.3, 25, and 9.4 ppm, respectively. Lesions in the forestomachs and lymphoid tissues have been rarely reported in cases of lead arsenate poisoning. In southern South America, these lesions are indistinguishable from those produced by Baccharis coridifolia, a toxic plant that contains macrocyclic trichothecenes, thus these conditions should be considered in the differential diagnosis of necrotizing lesions in alimentary and lymphoid organs.

Spontaneous Baccharis coridifolia Poisoning in Suckling Lambs

Background: Baccharis coridifolia is one of the most important and common poisonous plants in Rio Grande do Sul (RS) state, Brazil (RS). The intoxication occurs when native livestock are exposed to the plant for the first time, especially when they are hungry, thirsty and stressed after transportation. The lesions associated with the toxicosis are characterized necrosis of the epithelial lining of the pre-stomachs. Cases of intoxication by Baccharis spp. in sheep native of a certain farm are uncommon. The objective of this study is to report an outbreak of B. coridifolia poisoning in lambs in RS, Southern Brazil, and to address the epidemiological, clinical and pathological aspects of this condition.Cases: Ten 15-20 day-old Corriedale and Texel lambs from a lot of 150 were affected. The onset of clinical signs occurred two days after the lambs were moved from ryegrass (Lolium multiflorum) pasture to a native pasture with moderate amounts of sprouting B. coridifolia. Main clinical signs were intense abdominal pain, during which some lambs distended the thoracic and pelvic limbs while standing up, diarrhea, dehydration, ruminal atony, salivation, decubitus and death. Gross lesions in three necropsied lambs were mainly located in the digestive tract and included varying degrees of hyperemia, edema and erosions in the fore stomach mucosae. Histologically, there were hyperemia and degenerative, necrotic and ulcerative changes in the epithelial lining of forestomachs. The lesions observed were characterized by hydropic degeneration stratified mucosal epithelium and multifocal intercellular edema. Necrosis of individual epithelial cells, which had the intensely eosinophilic cytoplasm with a pyknotic or karyorrhetic nucleus, was observed. Multiple clefts were seen at the junction of the epithelium with the lamina propria, some of which containing intact and viable neutrophils. In addition, one of the sheep demonstrated focal extensive areas of moderate proliferation of granulation tissue in the submucosa of the forestomachs.Discussion: The diagnosis of B. coridifolia intoxication was based on the anatomopathological findings and on the presence of the plant in the pasture where the lambs were held. The lack of other plants, such as other species of Baccharis, Eupatorium tremulum and Baccharidastrum triplinervium, capable of producing a similar disease, reinforces the definitive diagnosis. Differently, from what is reported in the literature, the outbreak of B. coridifolia intoxication in this study occurred in lambs born on the farm. The toxicosis affected 15-20-day-old lambs, the age group in which lambs developing grazing habits. Similar to what occurred in an outbreak of B. megapotamica intoxication in lambs, it is probable that the lack of previous knowledge of the plant by the lambs was the main predisposing factor of the outbreak reported here. This is suggested by the involvement of only lambs and not adult sheep, the latter of course not native in relation to the plant. Affected lambs developed an acute clinical course with digestive signs. Deaths are usually related to pre-stomach injuries caused by the toxic action of macrocyclic trichothecenes, associated with dehydration and diarrhea, resulting in an electrolyte imbalance. Intoxication by B. coridifolia should be considered a differential diagnosis in lamb mortalities, mainly during the development of grazing habit. In order to avoid the occurrence of Baccharis coridifolia intoxication in sheep, it is recommended the previous adaptation with a gradual introduction of the sheep under close observation.

Aversão alimentar condicionada a Ipomoea carnea var. fistulosa em ovinos

Quinze ovinos foram adaptados ao consumo de Ipomoea carnea por 36 dias. Posteriormente, foram divididos ao acaso em três grupos de cinco ovinos cada e avertidos com cloreto de lítio (LiCl) (Grupo 1) e Baccharis coridifolia (Grupo 2). O Grupo 3 permaneceu como controle. Os ovinos foram desafiados ao consumo da planta na pastagem e em baias individuais até o 74° dia após o primeiro dia da aversão. Nos dias 14 e 19, o número de ovinos que consumiu I. carnea no Grupo 3 foi significativamente maior que o número de ovinos que consumiu a planta nos Grupos 1 e 2 (P=0,004 e P=0,0004, respectivamente). No dia 24, o número de ovinos que consumiu I. carnea foi significativamente maior no Grupo 3 do que no Grupo 1 (P=0,004). A partir do desafio do dia 29, não houve diferença significativa (P>0,05) no consumo da planta entre os três grupos. A quantidade de I. carnea consumida pelos ovinos do Grupo 3 durante o período do experimento no dia 7 após o primeiro dia da aversão foi significativamente maior do que o consumo das ovelhas dos Grupos 1 e 2 (P=0,0002 e P=0,01, respectivamente). Nos desafios seguintes, não houve diferença na quantidade de I. carnea ingerida pelos ovinos. Na avaliação do comportamento dos ovinos na pastagem infestada por I. carnea, o tempo destinado ao consumo da planta foi de no máximo 2,4%±1,6% do total de tempo de pastejo, não havendo diferença entre os três grupos. I. carnea nunca foi consumida avidamente pelos ovinos experimentais e a aversão incompleta induzida pelos dois agentes utilizados como aversores (LiCl e B. coridifolia) sugere que não seriam eficientes para reduzir ou eliminar o consumo de I. carnea pelos ovinos.

Methods of inducing conditioned food aversion to Baccharis coridifolia (mio-mio) in cattle

Three experiments were performed to determine the efficacy of various methods of averting naïve cattle to prevent Baccharis coridifolia poisoning: forced oral administration of 0.5g kg-1 body weight of fresh B. coridifolia; forced inhalation of the smoke from burning B. coridifolia and rubbing the plant on the animals' muzzles and mouths; and introducing the animals into paddocks with low invasion by B. coridifolia. Results demonstrated that cattle forced to ingest low doses become strongly averted if introduced into paddocks 23-26 hours after the aversion. In contrast, cattle introduced into the paddocks between 1-10 hours were not fully averted. Inhalation of B. coridifolia smoke, and rubbing the plant on the animals' muzzles and mouths were not efficient to induce an aversion. The introduction of cattle into paddocks with approximately 1% of B. coridifolia was efficient if the animals remained 5 months in the area, but not if they only remained for 60 hours, as cattle required sufficient time to learn to avoid the plant.

Conditioned food aversion to Ipomoea carnea var. fistulosa induced by Baccharis coridifolia in goats

Baccharis coridifolia is a plant that induces strong conditioned food aversion in ruminants. This research aimed to induce a conditioned food aversion to Ipomoea carnea var. fistulosa in goats, using B. coridifolia as an aversive agent, and to compare the aversion induced by this plant with the aversion induced by lithium chloride (LiCl). Thirteen goats were allotted into two groups: Group 1 with six goats was averted with 175mg/kg of body weight of LiCl and Group 2 with seven goats was averted with 0,25g/kg of bw of dried B. coridifolia. All goats were averted on day 1 after the ingestion of I. carnea. The aversion procedure with LiCl or B. coridifolia in goats from Groups 1 and 2, respectively, was repeated in those goats that again consumed the plant during tests on days 2, 3, and 7. The goats of both groups were challenged in pens on 23 and 38 days after the last day of aversion and challenged in the pasture on days 11, 15, 18, 20, 22, 25, 27 and 29 after the last day of aversion. After this period goats were challenged every 15 days on pasture until the 330º day after the last day of aversion (7th day). Two goats from Group 1 ingested I. carnea on the first day of the pasture challenge, 4 days after the last day of aversive conditioning in the pen. In addition, another goat in Group 1 started to consume the plant on day 18, and other two goats ate it on day 20. One goat in Group 1 that had never eaten I. carnea died on day 155. One goat from Group 2 started to ingest I. carnea on the first day of the pasture challenge, and a second goat started to consume this plant on day 182. At the end of the experiment, on day 330, the other five goats averted with B. coridifolia remained averted. These results suggest that B. coridifolia or an active compound from the plant could be used to induce aversion to toxic plants. Using B. coridifolia would be cheaper and, particularly in flocks with large number of animals, possibly easier than using LiCl, which requires the use of oral gavage and qualified personnel for its implementation.