Of browse, goats, and men: Contribution to the debate on animal traditions and cultures

The interaction of genes and environment on percent of juniper in the diet of goats divergently selected for high or low juniper consumption

Diet selection and preference by grazing animals are determined by genetic and environmental factors that interact and affect their efficacy for managing vegetation as targeted grazers and developing animals adapted to local grazing environments. The effect of the rearing environments on the consumption of juniper (Juniperus spp.) by goats that for 15 years were divergently selected for high (J+) or low (J-) percent juniper in their diet was investigated. To test the effect of rearing environment, at the end of the breeding season, pregnant does from both selection lines were grazed on either juniper-infested (JIR) or juniper-free (JFR) rangelands until their kids were weaned at about 75 days of age. Fecal samples were analyzed with fecal near-IR spectroscopy to determine the percent juniper in the diet. Fecal samples were collected from does on JIR when their offspring were 30 days of age and at weaning. Then, does that raised kids in both rearing environments grazed a common JIR pasture for a 28-day adaptation period before collecting fecal samples. After weaning, kids from both rearing environments grazed JIR for 22 days before collecting fecal samples. The J+ does always consumed more (P < 0.001) juniper than J- does, demonstrating different maternal role models for kids reared in the JIR environment. There was no effect of rearing environment (P = 0.488) or rearing environment × selection line interaction (P = 0.096) when J- and J+ does grazed a common JIR pasture. The percentage of juniper in J- kid diets (7%) was the same regardless of the rearing environment. However, the rearing environment did affect the percentage of juniper in the diet of J+ kids, resulting in a gene-environment interaction (P = 0.022). The percentage of juniper in the diet of J+ kids reared in JFR (16%) and JIR (24%) were about two and three times higher than J- kids, respectively, indicating that genetics and the rearing environment contributed about equally to the increase in the percentage of juniper in the J+ kid diets. Regardless of the rearing environment, the J+ kids had a higher percentage of juniper in their diets than J- kids (P < 0.001). Compared to males, female kids had a higher percentage of juniper in their diets (12 vs 17%, respectively; P = 0.002). The ability to select animals with specific dietary preferences holds promise for targeted grazing strategies to restore degraded rangelands, with potential applications in conservation and ecosystem management.

Selecting goats for juniper consumption did not improve their liver Phase I detoxification

A sodium pentobarbital-induced sleep time study was conducted on 15 adult intact male Boer × Spanish goats selected for high (J+, n = 7) or low (J-, n = 8) juniper consumption (estimated breeding values of 13.1 ± 1.0 and -14.3 ± 0.8, respectively; mean ± standard deviation). Pentobarbital sleep time is an in vivo assay of Phase I hepatic metabolism that can be induced by exposure to barbiturates and monoterpenes. Monoterpenes and pentobarbital are initially oxidized by this pathway; thus, we hypothesized that J+ goats would have shorter sleep times than J- goats. Time to the righting reflex after pentobarbital-induced sleep was measured in all goats following a minimum period of 21 d on three different diets: 1) grazing juniper-infested rangeland (JIR), 2) forage diet with no monoterpenes (M0), and 3) forage diet with 8 g/kg added monoterpenes from camphor, sabinene, and α-pinene in a w/w ratio of 5:4:1 (M+). Fecal samples from the JIR diet were analyzed with near-infrared spectroscopy for the percentage of juniper in the diet. Fecal samples from the JIR and M+ diets were analyzed for camphor and sabinene concentrations. The percentage of juniper in the diet of J+ goats grazing rangelands was greater (P = 0.001) than J- goats (31.1% and 18.6%, respectively). Sleep time did not differ between selection lines (P = 0.36). However, the sleep time of the goats fed M+ diet was 26 min shorter (P < 0.001) than JIR or M0 diets, which were equal. The concentration of camphor and sabinene in the feces was higher (P < 0.001) for goats on the M+ diet than on the JIR diet. There were no differences between selection lines in the serum enzymes indicative of liver disease (aspartate aminotransferase, bilirubin, gamma-glutamyl transferase, and glutamate dehydrogenase; P > 0.12), and all treatment means were within the reference interval. Selecting goats for juniper consumption did not affect the Phase I detoxification system, and several alternative hypotheses for differences in juniper consumption between J+ and J- goats are discussed.