Effects of supplement type and narasin inclusion on supplement intake by Bos indicus beef bulls grazing a warm-season forage.

This study aimed to evaluate the effects of supplement type and narasin inclusion on the frequency and supplement intake of grazing Bos indicus beef bulls. Four hundred animals were ranked by initial BW (383 ± 35 kg) and allocated into one of four paddocks of Brachiaria brizantha cv. Marandú (100 animals/paddock). Paddocks were randomly assigned to receive either a mineral salt (MIN) or a protein-energetic supplement (PREN) containing or not narasin (N) for a 90-d period. An individual electronic data capture system with 11 feed bunks was used to individually measure supplement intake and meal frequency in each paddock. The evaluations and analysis of individual intake, frequency of visits to the feeder, and intake per visit (I/V) were performed every 15 d and classified as periods (PR1 through PR6). All data were analyzed as a 2 × 2 factorial design with the PROC MIXED procedure of SAS. A supplement type × N × PR interaction was observed (P < 0.0001) for daily supplement intake. No differences were observed between MIN, whereas PREN had a greater (P ≤ 0.03) supplement intake on PR1 and PR3, but a reduced supplement intake on PR6 compared with PREN + N (P = 0.02). Moreover, no supplement type × N interaction (P = 0.47) or N (P = 0.44) effects were observed for daily supplement intake in the present study. A supplement type × N × PR interaction was detected (P < 0.0001) for the frequency of visits in the feeders. Throughout the experimental period, animals from the MIN + N had a greater (P ≤ 0.02) frequency of visits compared with MIN cohorts. A supplement effect was detected for I/V (P = 0.02), whereas neither a narasin effect (P = 0.74) nor interactions (P ≥ 0.16) were observed. Animals offered PREN had a greater I/V when compared with MIN cohorts (145 vs. 846 g/d for MIN and PREN, respectively; SEM = 16.1). When these data are reported as percentage of days visiting the feeder within each PR, MIN and MIN + N animals visited the feeder for 25.8% and 35.9% of the days, respectively. Conversely, no differences were observed (P = 0.65) in the overall mean visits per PR between PREN and PREN + N (12.8 vs. 12.3 d for PREN and PREN + N, respectively; SEM = 0.195). As percentage of days visiting the feeder, PREN and PREN + N visited the feeder for 85.1% and 81.9% of the days, respectively. In summary, narasin inclusion did not reduce supplement intake, regardless of supplement type, but increased the frequency of visits to the feeder for the MIN treatment.

Knockdown and mortality comparisons among spinosad-, imidacloprid-, and methomyl-containing baits against susceptible Musca domestica (Diptera: Muscidae) under laboratory conditions.

The activity of spinosad, imidacloprid, and methomyl baits and technical actives were assessed against susceptible house flies, Musca domestica L. (Diptera: Muscidae). In a feeding assay, imidacloprid affected flies more rapidly than methomyl or spinosad, but spinosad was 2.7 times more potent than methomyl and 8 times more potent than imidacloprid. The profile of technical actives correlated with their respective fly bait formulations in laboratory assays. Although having the most rapid onset of activity in laboratory tests, up to 50% of flies remained alive after exposure to imidacloprid bait. In contrast, <5% of flies survived 24-h exposure to spinosad or methomyl baits. High temperature reduced the knockdown activity of imidacloprid bait and slowed the speed of kill for spinosad and methomyl baits over a 24-h exposure period. Spinosad and methomyl baits were also superior to imidacloprid when applied to the floors of environmentally controlled rooms at label recommended rates, providing good fly control for up to 21 d. The fact that a significant percentage of flies exposed to imidacloprid were rapidly knocked down but subsequently remained alive in all of the assays suggested that flies were recovering from initial exposure to this compound. Given its favorable safety profile, a high degree of initial and residual activity comparable with methomyl and lack of cross-resistance to other chemistries, spinosad bait may be a valuable component of house fly control programs to help control or delay the emergence of resistant populations.

Ophthalmomyiasis (interna posterior) of the posterior segment and central nervous system myiasis: Cuterebra spp. in a cat.

A unilateral ophthalmomyiasis posterior in a 5-year-old female spayed Domestic Long-haired cat of a third or fourth stage instar Cuterebra spp. larvae is reported. The cat was presented for depression and anorexia. The organism was found on physical examination at presentation. The cat was euthanized because of the worsening systemic condition. The larva was demonstrated by histopathology with coagulation necrosis and hemorrhage of the optic nerve, retina and choroid, and anterior uveitis. No significant cerebrum and anterior brain stem lesions were found.