Relative palatability and efficacy of brodifacoum-25D conservation rodenticide pellets for mouse eradication on Midway Atoll

Invasive mice (Mus spp.) can negatively impact island species and ecosystems. Because fewer island rodent eradications have been attempted for mice compared to rats (Rattus spp.), less is known about efficacy and palatability of rodenticide baits for mouse eradications. We performed a series of bait acceptance and efficacy cage trials using a standard formulation of brodifacoum-based rodenticide on wild-caught mice from Sand Island, Midway Atoll, to help inform a proposed eradication there. Mice were offered ad libitum brodifacoum pellets along with various alternative food sources, and a “no choice” treatment group received only bait pellets. Mortality in the no choice trial was 100%; however, when offered alternative foods, mice preferred the alternative diets to the bait, leading to low mortality (40%). Because there was concern that the bittering agent Bitrex® in the formulation may have reduced palatability, we conducted a subsequent trial comparing brodifacoum bait with and without Bitrex. Mortality in the with-Bitrex treatment group was slightly higher, indicating that the bittering agent was not likely responsible for low efficacy. Laboratory trials cannot account for the numerous environmental and behavioral factors that influence bait acceptance nor replicate the true availability of alternative food sources in the environment, so low efficacy results from these trials should be interpreted cautiously and not necessarily as a measure of the likelihood of success or failure of a proposed eradication.

Preference of Boer goats for Namibian native forage legumes and Lucerne (Medicago sativa)

The objective of this study was to determine the relative palatability of four native forage legumes (Otoptera burchellii, Crotalaria argyraea, Crotalaria podocarpa and Vigna lobatifolia) in comparison with each other and with Lucerne (Medicago sativa). Eight weaned Boer goats aged 6 months and weighing 25.2 ± 4.9 kg were grouped by sex, and then randomly allocated to individual pens. Goats were simultaneously offered 100 g of each of the four native legumes and 600 g of M. sativa (as-is basis) over a 10-day period. Grass hay (Cenchrus ciliaris), fresh water and mineralised salt licks were available at all times. Grass hay was given to allow diet mixing and possibly ameliorate any undesirable effects, such as bloat, due to feeding on legumes alone. The percentage of each species consumed of that offered was associated (P < 0.001) with legume species, day and legume × day interaction. Over 95% of the O. burchellii, V. lobatifolia and Lucerne offered were consumed from Days 1 to 10. The amounts of Crotalaria spp. consumed fluctuated widely in the first 4 days, but increased thereafter to >95% of that offered. This study demonstrated that hay of all the four native forage legume hays were palatable to Boer goats, with the inferred ranking being: (Lucerne, V. lobatifolia) > O. burchellii > Crotalaria spp. Further studies are required to investigate the productivity of goats feeding on these native forage legumes, which have potential for use in marginal lands.

Voluntary Intake and Palatability Indices of Pedi Goats fed Different Levels of Acacia karroo Leaf Meal by Cafeteria Method

A study was conducted to determine preference intake and relative palatability indices of tanniniferous Acacia karroo fed to 5 growing male Pedi goats with an average body weight of 19.81 ± 1.83kg. Five feeding troughs were provided to each goat and each animal was exposed to all the experimental diets. A cafeteria feeding approach was used, thus, permitting goats free access to the diet of their choice. Acacia karroo (K) was offered in a mixture with Setaria verticillata (S) hay at five different levels: Diet 1: S80K20, Diet 2: S75K25, Diet 3: S70K30, Diet 4: S60K40 and Diet 5: S50K50. The daily relative palatability indexes (RPI) obtained for each diet were subjected to analysis of variance with feeds as treatments and individual animals as replicates in a completely randomized design. Significant differences (P Diet 4> Diet 3> Diet 2> Diet 1. Diet 5 appeared to be the most preferred by goats with an RPI of 96.91%. Palatability indices were positively and significantly (Pand tannin contents. Results of this study indicate that tannin-rich Acacia karroo leaves when fed in a mixed diet can influence preference and intake by Pedi goats. Palatability studies could be used in designing supplemental feeding programs for ruminant livestock in the tropics.