To compare the effects of a low-starch, high-fibre diet [LSHF; 51.6% neutral detergent fibre (NDF), 3.0% starch, 14.8% crude protein (CP)] and a high-starch, low-fibre diet (HSLF; 33.3% NDF, 20.0% starch, 19.6% CP) on the nutritional status of captive exotic ruminants, 16 mule deer (Odocoileus hemionus) were fed one of these two diets ad libitum with ≤25% alfalfa hay cubes from 10 days to 68 weeks of age. During five sampling periods beginning in November and spaced 6-12 weeks apart thereafter, feed intake, rumen and blood chemistry, faecal scores, growth and body condition were measured. Dry matter intake, digestible energy intake, time spent ruminating and feeding and blood acetate concentration were greater for deer fed LSHF (p < 0.05 for all). Lower dietary CP led to reduced blood urea nitrogen for deer consuming LSHF (p = 0.004). Deer had the same faecal scores, growth and body fat among treatments (all p > 0.05). These findings show pelleted diets with less starch, more fibre, and reduced protein met the energy and protein requirements of growing mule deer, a medium-sized browsing ruminant, as well as traditional grain-based diets while more closely mimicking natural forages and stimulating a more natural feeding behaviour.

A two‐year, small‐plot study was conducted to evaluate plant growth‐promoting rhizobacteria (PGPR) for biofertilization of fall‐stockpiled bermudagrass [Cynodon dactylon (L.) Pres.]. Eighteen, 10.8‐ft2 bermudagrass (cultivar ‘Coastal’) plots were mowed to 1‐inch stubble height prior to stockpiling. Experimental treatments included a negative control, synthetic fertilizer, PGPR single‐strain DH 44, DH 44 + fertilizer, PGPR multiple‐strain Blend 20, and Blend 20 + fertilizer (n = 3). Two PGPR applications were made, one at the beginning of each stockpiling season in mid‐August, and again 30 days later. Ammonium sulfate was applied at 50 lb N/acre concurrent with the first PGPR application. Each plot was divided into three subplots, which were harvested at different periods (i.e., mid‐November, mid‐December, and mid‐January) of each year to determine forage dry matter (DM) yield and nutritive value. Forage DM yield was greatest (P ≤ .03) for Blend 20 + fertilizer, but it was not different (P = .26) from that of the synthetic fertilizer treatment. Concentration of crude protein was least (P < .04) for DH 44 and Blend 20 treatments. Concentrations of acid detergent fiber were not different among treatments, except for the negative control which was lower (P < .05). In vitro true digestibility was not different (P < .05) among treatments. These results indicate that PGPR may be a viable option for biofertilization; however, further investigation into the effect of PGPR inoculants at field level is needed.

No abstract

Forage production practices have been greatly affected by the increasing cost of N fertilization. Therefore, supplemental and alternative N sources are needed to ensure the economic viability of these systems. A 2-yr, small plot study was designed to evaluate plant growth-promoting rhizobacteria (PGPR) as an alternative form of N fertilizer for fall-stockpiled bermudagrass (Cynodon dactylon). Eighteen 1-m2 ‘Coastal’ bermudagrass plots were treated with a synthetic N fertilizer, DH44 (PGPR strain), DH44+fertilizer, Blend 20 (PGPR blend), Blend 20+fertilizer, and a control, then stockpiled through the fall. Two PGPR applications were applied in late-August and again 30 d later. Fertilizer and PGPR+fertilizer plots received (NH4)2SO4, at a rate of 56 kg N/ha. One-third of each plot was clipped to 2.5 cm in November, December, and January, respectively. Forage DM yield, CP, NDF, ADF, and ADL were determined via wet chemistry at the Auburn University Ruminant Nutrition Laboratory (Auburn, AL). Data were analyzed using PROC MIXED (SAS 9.4, SAS Inst., Cary, NC) as a completely randomized design. Yield was greatest (P ≤ 0.0318) for Blend 20+fertilizer, but it was not different (P = 0.2552) from that of the synthetic fertilizer (1,914 kg ha-1, 1,768 kg ha-1, respectively). Concentration of CP was least (P ≤ 0.0437) for DH44 and Blend 20 treatments (90 g kg-1 and 92 g kg-1, respectively). Concentrations of NDF for the control were different (P ≤ 0.0045) for all treatments except synthetic fertilizer (P = 0.1092). Concentrations of ADF were not different (P ≥ 0.1613) excluding the control (P ≤ 0.0525; 342.8 g kg-1and 358.0 g kg-1, respectively). In vitro true digestibility (IVTD) was not different (P = 0.0947) among all treatments (463.1 g kg-1). All yield and nutritive value parameters were greater (P ≤ 0.0246) in Year 2. These results indicate that PGPR is a viable option for biofertilization of fall-stockpiled bermudagrass; however, further investigation into the effects of PGPR inoculants at a field scale are needed.

Plant growth-promoting rhizobacteria (PGPR) are non-pathogenic, soil-inhabiting, beneficial bacteria that colonize the roots of plants. Some PGPR strains are reported to increase nutrient uptake and fix atmospheric N, which suggests that biofertilization with PGPR may provide an alternative to N fertilization for forage production. In mid-August 2017, a study was initiated to evaluate PGPR as an alternative form of N fertilization for fall-stockpiled bermudagrass. Eighteen 1-m2plots were mowed to a 2.5-cm stubble height prior to stockpiling. Two strains of PGPR (Blend 20 and DH44) were selected for evaluation based on performance in greenhouse trials. Treatments included: control, fertilizer, DH44, DH44+fertilizer, Blend 20, and Blend 20+fertilizer (n = 3).Two applications of PGPR were applied at the beginning of the stockpiling season and 30 d later. Ammonium sulfate was applied at 56 kg/ha during the first PGPR application. Plots were clipped to a height of 2.5 cm in mid-November, December, and January to determine yield and nutritive value. Data were analyzed using PROC MIXED (SAS 9.4) as a completely randomized design.Yield was greater (P ≤ 0.007) for Blend 20+fertilizer, DH44, and Blend 20 (695, 673, and 664 kg DM/ha, respectively) than the control (598 kg DM/ha). Forage DM yield differed among harvest dates, with Blend 20+Fertilizer having the highest yield in January (835 kg DM/ha). Blend 20+fertilizer, control, and fertilizer treatments had the greatest effect on CP concentration (9.1, 9.5, and 10.1%, respectively). Concentrations of NDF and ADF were greatest (P ≤ 0.01) for Blend 20, Blend 20+fertilizer, DH44, and fertilizer. Percentage IVTD decreased with the later harvests (46.1, 33.8, and 39.0% in November, December, and January, respectively); however, CP was unchanged across all harvests (P3 0.12). Overall, PGPR increased DM yield of stockpiled bermudagrass while maintaining forage nutritive value similar to commercial fertilizer.