Effects of Juniperus species and stage of maturity on nutritional, in vitro digestibility, and plant secondary compound characteristics

Genetic background of juniper (Juniperus spp.) consumption predicted by fecal near-infrared spectroscopy in divergently selected goats raised in harsh rangeland environments

BACKGROUND

Junipers (Juniperus spp.) are woody native, invasive plants that have caused encroachment problems in the U.S. western rangelands, decreasing forage productivity and biodiversity. A potential solution to this issue is using goats in targeted grazing programs. However, junipers, which grow in dry and harsh environmental conditions, use chemical defense mechanisms to deter herbivores. Therefore, genetically selecting goats for increased juniper consumption is of great interest for regenerative rangeland management. In this context, the primary objectives of this study were to: 1) estimate variance components and genetic parameters for predicted juniper consumption in divergently selected Angora (ANG) and composite Boer x Spanish (BS) goat populations grazing on Western U.S. rangelands; and 2) to identify genomic regions, candidate genes, and biological pathways associated with juniper consumption in these goat populations.

RESULTS

The average juniper consumption was 22.4% (± 18.7%) and 7.01% (± 12.1%) in the BS and ANG populations, respectively. The heritability estimates (realized heritability within parenthesis) for juniper consumption were 0.43 ± 0.02 (0.34 ± 0.06) and 0.19 ± 0.03 (0.13 ± 0.03) in BS and ANG, respectively, indicating that juniper consumption can be increased through genetic selection. The repeatability values of predicted juniper consumption were 0.45 for BS and 0.28 for ANG. A total of 571 significant SNP located within or close to 231 genes in BS, and 116 SNP related to 183 genes in ANG were identified based on the genome-wide association analyses. These genes are primarily associated with biological pathways and gene ontology terms related to olfactory receptors, intestinal absorption, and immunity response.

CONCLUSIONS

These findings suggest that juniper consumption is a heritable trait of polygenic inheritance influenced by multiple genes of small effects. The genetic parameters calculated indicate that juniper consumption can be genetically improved in both goat populations.

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.

Impact of camphor on the in vitro mixed ruminal microorganism fermentation from goats selected for consumption of low and high levels of Juniperus spp. 1

Encroaching plant species in West Texas continues to significantly reduce livestock production capacity and cause an imbalance between plant and livestock ecology. Juniperus ashei and Juniperus pinchotii are encroaching species rarely used by browsing animals, mainly due to phytochemical defenses. Juniperus spp. contain large concentrations of monoterpenes in their essential oil profiles to deter herbivory. Since 2003, two divergent bloodlines of meat goats have been selected to consume low or high (LJC or HJC) amounts of juniper foliage, through screening fecal samples with near-infrared reflectance spectroscopy. However, it remains unclear whether HJC goats expressed a physiological ability to consume a greater amount of juniper or if they were colonized by a ruminal microbial population that could detoxify juniper phytochemicals. Therefore, this study aimed to investigate the impact of 0.00 and 1.97 mM of camphor on the mixed ruminal microorganism fermentation after 0, 1, 2, 4, 12, and 24 h of incubation. Five LJC and five HJC goats were fed a juniper-free diet (n = 10) and five LJC and five HJC goats (n = 10), were fed a diet containing 30% fresh J. ashei leaves for 21 days prior to ruminal fluid collection. In vitro fermentations used LJC and HJC, ruminal fluid inoculum was added (33% v/v) to anoxic media in sealed Balch tubes. Total short-chain fatty acid (SCFA) production and acetate to propionate ratio were increased (P < 0.05), but there was no effect on pH (6.56 ± 0.09). Goats that received the juniper-free diet had higher (P < 0.05) SCFA production than juniper-containing diets. There was no consistent difference in LJC and HJC microbial fermentation end products caused by the addition of 1.97 mM of camphor, and goats receiving a juniper-free diet consistently generated more SCFAs in the presence of 1.97 mM of camphor. Furthermore, bloodline differences in juniper consumption were likely related to physiological adaption capacities within the animal and not a ruminal microbial detoxification advantage.

Effects of feeding juniper as a roughage on feedlot performance, carcass measurements, meat sensory attributes, and volatile aroma compounds of yearling Rambouillet wethers1,2

The majority of U.S. lambs are born during late winter or early spring, which can create downstream variability in carcass quality if commercial lamb harvest is to be relatively constant throughout the year. Flavor is an important quality determining characteristic of sheep meat and is influenced, in part, by animal age at harvest. However, management practices to mitigate the risk of objectionable flavors in meat from old crop lambs or yearlings are not well known. Yearling (16.8 ± 0.14 mo) Rambouillet wethers were assigned to 1 of 3 treatment groups, which consisted of feeding a 20% ground sorghum-sudangrass hay diet for 40 d (JUN0; n = 10), a 20% ground juniper diet for 40 d (JUN40; n = 10), or a 20% ground hay diet for 20 d followed by a 20% ground juniper diet for 20 d (JUN20; n = 10). Wethers were harvested on day 41 and a whole bone-in loin and a boneless inside leg roast were fabricated from one side each of carcass. After grilling (loin chop) or convection air roasting (leg roast), trained sensory panel evaluation and measurement of aroma volatiles by gas chromatography/mass spectrometry were performed. Treatment diet did not affect (P ≥ 0.17) wether feedlot performance, dressing percentage, or loin eye area. However, wethers fed JUN0 tended (P = 0.06) to have greater back fat depth than wethers fed JUN20 or JUN40. No trained sensory panel trait of loin chop samples was affected (P > 0.10) by treatment. Leg roasts from JUN0 and JUN20 wethers had greater (P = 0.01) lamb identification sensory score than JUN40. Benzaldehyde, 1-heptanol, and 1-octanol concentrations were greater (P < 0.05) and decanal and nonenal concentrations were less (P < 0.05) in loin chops from JUN0 compared with JUN40 wethers. Additionally, the terpenes cedr-8-ene, gamma muurolene, and widdrene tended to be greater (P < 0.07) in loin chops from JUN20 and JUN40 than JUN0 wethers. The 2-pentyl-furan concentrations were greatest (P = 0.03) in leg roasts from JUN40 wethers. Like the loin chops, cedr-8-ene, gamma-muurolene, toluene, and widdrene were greater (P < 0.05) in leg roasts from wethers fed either of the juniper diets compared with JUN0. Yearling wethers can be finished on a feedlot diet containing 20% juniper for up to 40 d prior to harvest with no impact on feedlot performance, carcass characteristics, nor negative impact on sensory attributes or volatile compounds of either grilled loin chops or roasted legs.

Substituting ground woody plants for cottonseed hulls in kid goat feedlot diets: growth performance and blood serum chemistry

Boer × Spanish kid goats (n = 48) were used to evaluate effects of using ground woody products in feedlot diets on growth performance and blood serum chemistry. A completely randomized study design was used with 2 feeding periods (Period 1 = 70% concentrate, days 0 to 26; Period 2 = 86% concentrate, days 27 to 64). Goats were individually fed 1 of 6 diets that differed only by roughage source (n = 4 wether males and 4 females/treatment; initial BW = 22 ± 2 kg): cottonseed hulls (CSH; control) or ground wood consisting of redberry (RED), blueberry (BLUE), one-seed (ONE), or eastern red cedar (ERC) Juniperus spp., or Prosopis glandulosa (MESQ). Ground woody diets were individually compared with CSH. During Period 1, goats fed CSH had greater (P < 0.05) average daily DMI (DMI), ADG, and G:F than goats fed MESQ and tended to have greater (P < 0.10) ADG and G:F than goats fed BLUE. A Treatment × d interaction (P = 0.008) was observed for goat BW during Period 1 and goats fed CSH tended (P < 0.09) to have greater BW on day 27 than goats fed BLUE or MESQ. During Period 2, Treatment × d interactions were not observed (P > 0.29) for DMI, ADG, G:F, or BW and no differences were observed between goats fed CSH and goats fed any of the treatment diets. Various blood serum variables were different between CSH and goats fed diets containing woody plants (mainly during Period 1); however, blood serum profiles did not indicate hepatotoxicity or any other health issue. Collectively, results suggested that ground Juniperus pinchotii, Juniperus ashei, or Juniperus monosperma can completely replace CSH in goat feedlot diets without negatively affecting growth performance or animal health. During Period 1, feeding diets to goats that contain 30% Juniperus virginiana (ERC) or P. glandulosa (MESQ) may not be economically justifiable in most scenarios, even though goat health, assessed by blood serum profiles, was not negatively affected. However, using 14% J. virginiana (ERC) or P. glandulosa (MESQ) in finishing diets is warranted.

Protein dietary efficiency and methane emission in cattle fed soybean meal treated with tannins

Adding tannins to the dietary protein source will cause complexation between the tannin and protein, which may increase dietary ruminal undegraded protein. Thus, this study aimed to evaluate the effects of replacing soybean meal (SM) with soybean meal treated with tannin (SMT) on the intake, partial and total nutrient digestibility, and protein dietary efficiency of young cattle fed a high-concentrate diet. Five Nellore bulls with bodyweights of 290 ± 11.2 kg were fitted with ruminal and abomasal cannulas and were used in the study. The experimental diets included 7.5% SM, with a proportion of that SM (0%, 33%, 66% or 100%) replaced with SMT. Another treatment (SMT+urea) with only 2.5% SM treated with tannins was tested. The intake of ether extract and the intake of neutral detergent fibre ash and protein were the only parameters related to feed intake that were affected by the replacement of SM with SMT. Ruminal and intestinal digestibility each showed a linear effect on crude protein, which decreased with ruminal digestibility and increased with intestinal digestibility. The intake of ruminal undegraded protein and metabolisable protein showed a positive linear correlation with the amount of SMT in the diet. SMT substitution showed no effect on methane emission. The replacement of traditional SM with SM treated with 2.5% tannins (85% condensed tannins and 15% hydrolysable tannins) for cattle that were fed high-concentrate diets showed increased amounts of metabolisable protein and decreased nitrogen loss per unit of crude protein, without changing the methane emission.