Anthelmintic resistance in sheep in the semiarid region of Minas Gerais, Brazil

Anthelmintic efficacy was evaluated among sheep that had become naturally infected with gastrointestinal nematodes in 17 flocks located in the semiarid region of Minas Gerais, Brazil. Feces were collected individually from 1021 hairy sheep to determine the number of eggs per gram of feces (EPG) and for coprocultures to identify nematode genera the nematodes. Only the animals that presented EPG counts greater than or equal to 200 were included in the study (totaling 381 sheep). The animals were divided into three treatment groups: albendazole, ivermectin and levamisole. Fourteen days after the administration of anthelmintics, fecal samples were taken from all animals. In each flock, the pre-treatment and post-treatment arithmetic mean EPG were used to calculate the efficacy (FECR) for each of the treatment groups and the lower 95% confidence limit. Data were analyzed with the "eggCounts 2.3" package in RStudio, using a Bayesian model for paired design. The anthelmintics were classified as being efficacious (when the FECR was both equal to or above 95% and the lower 95% confidence limit was equal to or above 90%) or as encountering anthelmintic resistance (when the FECR was below 95% and the lower 95% confidence limit was below 90%) or inconclusive (when none of the other criteria were fulfilled). Albendazole and ivermectin were not effective in any of the flocks. Levamisole was effective against gastrointestinal nematodes in 25% of the flocks studied. Haemonchus, Trichostrongylus and Oesophagostomum genera were identified in this study in a semiarid region of Minas Gerais, Brazil. The genus Haemonchus was the most prevalent, followed by Trichostrongylus and Oesophagostomum. After anthelmintic treatment, the most prevalent genus was Haemonchus, followed by Trichostrongylus; the genus Oesophagostomum was not detected. The highest percentage of Haemonchus larvae was observed after treatment with ivermectin, followed by albendazole and levamisole. This study revealed the existence of gastrointestinal nematodes in sheep that present multiple resistance to all three main classes of anthelmintic drugs.

Anthelmintic efficacy in strongyles of horses in Northern Minas Gerais, Brazil

The intensive use of anthelmintics has resulted in resistant parasite populations in horses. The objective of this trial was to evaluate the anthelmintic efficacies of the anthelmintics fenbendazole, ivermectin and abamectin in 24 horse farms in Northern Minas Gerais. Egg counts per gram of faeces (EPG) were performed individually in 619 animals. Animals presenting EPG counts greater than or equal to 150 were used in the tests on faecal egg count reduction (FECR), totalling 436 equines. These animals received the anthelmintics, fenbendazole, ivermectin, and abamectin. Faeces were collected 14 days after the administration of anthelmintics to perform the EPG. Pre- and post-treatment EPG counts were used to calculate the FECR for each anthelmintic group, and faecal culture was used to identificy of the strongyles. The resistance status was evaluated based on the FECR and LCL95%. Fenbendazole was effective in 11 (45.8%) of the horse farms. Ivermectin was effective in 17 (77.3%) and abamectin in 17 (74%) of the farms; side-resistance was detected in 3 (12.5%) of the farms. Intestinal strongyle resistance to anthelmintics was observed in 14 (58.3%) of the farms. Cyathostomin larvae were found in 100% of the farms, Strongylus vulgaris in 13 (54.2%), and S. equinus in 3 (12.5%). Only cyathostomins larvae were detected post-treatment with ivermectin and abamectin.

Effects of different banana crop wastes on nutrient intake and digestibility, microbial protein synthesis, feeding behavior, and animal performance of ¾ Holstein × Zebu heifers in a semiarid rangeland

The objective of this study was to evaluate the use of banana crop wastes in diets of ¾ Holstein × ¼ Zebu heifers on the intake and digestibility of nutrients, microbial protein synthesis, feeding behavior, and animal performance. Eight ¾ Holstein × ¼ Zebu heifers were utilized with an average age of 18 ± 1.0 months and an average body weight (BW) of 298 ± 3.06 kg. The experiment was distributed in two simultaneous 4 × 4 Latin squares. The treatments were as follows: Diet 1 (SS)-sorghum silage as exclusive dietary roughage; diet 2 (SSL)-sorghum silage (50%) associated with 50% leaf hay of banana trees (on a DM basis); diet 3 (SSBP)-sorghum silage (50%) associated with 50% banana peel hay; and diet 4 (SSPS)-sorghum silage (50%) associated with 50% pseudostem hay of banana trees. The roughage:concentrate ratio was 75:25. The greatest dry matter intake (DMI; p < 0.01) was found in heifers that received the SS and SSBP diet, mean of 10.19 kg/day. The SS diet showed greatest dry matter digestibility (DMD; p < 0.01) and crude protein digestibility (CPD; p < 0.01). The concentration of total purines (p < 0.01) and absorbed purines (p < 0.01), microbial protein synthesis (p < 0.01), and microbial efficiency (p < 0.01) was higher in the SSBP diet in comparison with SS and SSL diets. The longest eating time was observed in animals that received the SSL diet, being 17.79% higher (p = 0.01) than the SSBP diet. The final BW (p = 0.39) and BW gain (p = 0.39) were similar, with averages of 319.84 kg and 1.08 kg/day, respectively. Biometric measurements were not altered as a function of bedtime (p > 0.05). Banana wastes can be used to feed ¾ Holstein × ¼ Zebu heifers in partial replacement for sorghum silage as they do not alter the animals' weight gain and body development.

Mineral content of longissimus lumborum from growing lambs fed crude glycerin

The objective of the study was to evaluate whether crude glycerin (CG), which was supplied as a dietary ingredient for growing lambs, affected the macro- and micromineral contents of the longissimus lumborum (LL). Twenty-four lambs were placed in two treatments: animals that received no CG and animals that received CG as part of their diet. The experiment lasted for 56 days. The phosphorus, potassium, magnesium, calcium and chromium contents in the LLs of the lambs were not significantly different between the groups. Cadmium, nickel and lead were not detected in the LLs of lambs fed CG. The zinc, iron and copper contents decreased in the LLs of lambs fed CG (approximately 10%, 14%, and 30%, respectively) (P ≤ .03). The sodium content in the LLs increased with the inclusion of CG in the diet (11%) (P = .029). We concluded that the zinc, iron and copper contents decreased in the LLs of the lambs fed CG and sodium content increased.

Nutritional efficiency of feed-restricted F1 Holstein/Zebu cows during the middle third of lactation

Objective

The objective of this study was to evaluate the effects of different levels of quantitative feed restriction on nutrient intake and digestibility, nitrogen balance, efficiency and feeding behavior, and productive performance in F1 Holstein/Zebu cows during the middle third of their lactation.

Methods

Sixty F1 Holstein/Zebu cows with 111.5±11.75 days of lactation and an initial body weight (BW) of 499±30 kg (mean±standard error of the mean) were used. The experimental design was completely randomized with the following diet levels of feed restriction: 3.39%, 2.75%, 2.50%, 2.25%, and 2.00% of BW, with 12 replications for each level. The experiment lasted for 63 days, of which each period lasted 21 days with the first 16 days for diet adaptation followed by 5 days for collection of data and samples.

Results

For each 1% of BW diet restriction, there was a decrease in dry matter intake of 5.26 kg/d (p<0.01). There was no difference in daily milk production (p = 0.09) under the restriction levels of 3.39% to 2.0% of BW. When corrected for 3.5% fat, milk production declined (p = 0.05) 3.46 kg/d for each percentage unit of feed restriction.

Conclusion

Restricting the feed supply for F1 Holstein/Zebu cows in the middle third of their lactation period altered nutrient intake, nitrogen balance and ingestive behavior but did not affect milk production or feed efficiency. However, considering the observed BW loss and decrease in milk production corrected for 3.5% fat, restriction of no less than 2.5% BW is recommended.

Nutritional and productive parameters of Holstein/Zebu cows fed diets containing cactus pear

Objective

This study ascertained effects of cactus pear in association with different roughage in the diet of F1 Holstein/Zebu cows on intake, nutrient digestibility, nitrogen balance, ingestive behavior and performance.

Methods

Eight cows with 72 ± 11 days of lactation were used. The experimental design was simultaneous in two 4 x 4 Latin squares. Four experimental diets were used: Diet 1 - sorghum silage as exclusive roughage; Diet 2 - sorghum silage associated with cactus pear in a proportion of 50% of the roughage (dry basis); Diet 3 - elephant grass (Pennisetum purpureum cv. Roxo) as exclusive roughage; Diet 4 - elephant grass associated with cactus pear in a proportion of 50% of the roughage. The roughage:concentrate ratio was 75:25. Dry matter intake (P = 0.01) was higher with sorghum silage.

Results

There were differences in dry matter intake (P = 0.01), crude protein (P <0.01), ether extract (P = 0.01), non-fibrous carbohydrates (P <0.01) and total digestible nutrients (P = 0.01) among the diets. Cactus pear in the diet reduced water intake by 44.52% (P < 0.01). The nitrogen balance was 59.71% and 27.49% lower in animals treated with exclusive sorghum silage and sorghum silage associated with cactus pear in relation to diets with elephant grass and elephant grass associated with cactus pear, respectively (P < 0.01). The diets did not influence the milk production (P = 0.70), 3.5% fat corrected milk production (P = 0.72) or feed efficiency (P = 0.61).

Conclusion

The association of cactus pear with sorghum or elephant grass silage does not alter milk production, reduces the intake of dry matter and water and improves the digestibility of nutrients.