No abstract

The design and validation of a combined targeted selective treatment (C-TST) scheme to control gastrointestinal nematodes (GIN) of goats under tropical conditions is described. A survey performed on 1585 goats (older than 4 months) from 103 smallholder subsistence farms from tropical México (Yucatán), showed the classical over-dispersion distribution of the GIN fecal egg excretions (FEC) indicating that most goats had a low excretion of eggs and only a few had high FEC. A second stage of the survey (20 farms) tested the association between FAMACHA© and packed cell volume (PCV) (n = 638) as well as FAMACHA© and FEC (n = 627). The survey showed that FAMACHA© was a good tool to identify anemic animals but no association was found with their FEC. As a result, we proposed to combine FAMACHA© with body condition score (BCS) to identify adult animals at risk of high GIN infections. The FEC was used to identify goats needing anthelmintic (AH) treatment. The C-TST scheme was surveyed in a goat farm (mean 138 adult goats/year) in Yucatán for 6 years (8292 events recorded). In that period, the mean number of goats left without AH treatment was 57.4%. Meanwhile, nearly 30% of the goats needed only one treatment per year. Less than 15% of the goats required 2 or more treatments per year. Besides, the AH doses were distributed amongst small number of animals every month throughout the year. Thus, under the browsing conditions of Yucatán, México, the combination of BCS and FAMACHA© can be used as a screening procedure to identify animals at risk of severe GIN infections and the FEC help to reduce the number of goats treated per year with no apparent negative consequences on the goats.

No abstract

This trial evaluated the effect of maize supplementation on the ingestive behavior, nutrient intake and the resilience against gastrointestinal nematode (GIN) infection of hair sheep in a silvopastoral system containing tropical grasses and legume trees. In addition, it attempted to determine the metabolic cost of the natural GIN infection in supplemented and non-supplemented animals. Twenty-nine 3-month-old lambs (male and female), raised nematode free, were allocated to four groups: I-NS (infected, not supplemented, n = 8), I-S (infected, supplemented with maize at 1.5% live weight (LW), n = 7), T-NS (treated with moxidectin 0.2 mg/kg LW every 28 days, and not supplemented, n = 7) and T-S (treated with moxidectin and supplemented with maize at 1.5% LW, n = 7). During the 70-day trial, fodder intake, fodder selection, LW change (LWC), red blood cell counts (RBC), hemoglobin (Hb), hematocrit (Ht) and eggs per gram of feces (EPG) were measured every 14 days. Supplement consumption was recorded daily. Metabolizable energy (ME) and protein (MP) consumption from the feeds were estimated. Maize supplementation helped to improve the resilience of hair sheep lambs against GIN infections. The I-S and T-NS groups showed similar LWC, RBC, Hb and Ht (P > 0.05) and both were higher than those in the I-NS group (P < 0.05). No difference was found in EPG between the I-NS and the I-S groups (P > 0.05). No effect of sex was observed in the different variables. Although all groups showed low dry matter intake (DMI) (< 2% LW), supplemented groups (T-S and I-S) showed higher total DMI (fodder + maize; P < 0.05), hence higher ME and MP intakes than the non-supplemented groups (T-NS and I-NS). All groups showed similar fodder selection patterns. The estimated metabolic cost of parasitism was ME = 0.70 MJ/day and MP = 9.2 g/day in the I-S animals. Meanwhile, the cost in the I-NS animals was ME = 1.46 MJ/day and MP = 12.71 g/day. Maize supplementation was an economically viable strategy to control GIN compared with no intervention.

The effect of maize grain supplementation on the resilience and resistance of browsing Criollo goat kids against gastrointestinal nematodes was evaluated. Five-month-old kids (n = 42), raised worm-free, were allocated to five groups: infected + not supplemented (I-NS; n = 10), infected + maize supplement at 108 g/d (I-S108; n = 8), maize supplement at 1% of body weight (BW) (I-S1%; n = 8), maize supplement at 1.5% BW (I-S1.5%; n = 8), or infected + supplemented (maize supplement 1.5% BW) + moxidectin (0.2 mg/kg BW subcutaneously every 28 d) (T-S1.5%; n = 8). Kids browsed daily (7 h) in a tropical forest for 112 days during the rainy season. Kids were weighed weekly to adjust supplementary feeding. Hematocrit (Ht), hemoglobin (Hb), and eggs per gram of feces were determined fortnightly. On day 112, five goat kids were slaughtered per group to determine worm burdens. Kids of the I-S1.5% group showed similar body-weight change, Ht and Hb, compared to kids without gastrointestinal nematodes (T-S1.5%), as well as lower eggs per gram of feces and Trichostrongylus colubriformis worm burden compared to the I-NS group (P > 0.05). Thus, among the supplement levels tested, increasing maize supplementation at 1.5% BW of kids was the best strategy to improve their resilience and resistance against natural gastrointestinal nematode infections under the conditions of forage from the tropical forest.