PSX-B-3 Effect of infrequent nitrogen supplementation on forage utilization

Our objective was to determine the effects of differing levels of supplemental nitrogen offered daily, or every 3 d on nitrogen balance, forage intake, and digestibility in cattle consuming low-quality forage. Five ruminally cannulated Angus × Hereford steers (BW = 350 ± 71 kg) were used in a 5 × 5 Latin square design. Steers consumed low-quality bluestem hay (67.7% NDF, 4.7% CP; DM basis) ad libitum. Treatments were no supplement (CON), or cottonseed meal offered at levels providing 120 mg N/kg BW each day (L/1D) or every 3 d (L/3D), 240 mg N/kg BW every 3 d (M/3D), or 360 mg N/kg BW every 3 d (H/3D). Hay, ort, urine, and fecal samples were collected during the last 6 d of each period and ruminal fluid during the last 3 d. Total digestible OM intake was greater in L/1D (6660 g/d; P < 0.01) compared to CON (4498 g/d) and increased linearly in steers supplemented intermittently (5145, 6170, and 6698 g/d for L/3D, M/3D, and H3/D, respectfully; P < 0.01). Total tract OM digestibility was similar between CON and L/1D, L/3D, and H/3D (58.21, 61.21, 60.82, and 60.91%, respectively; P ≥ 0.10) but was greater in M/3D steers (63.30%; P ≤ 0.02). Reducing frequency of protein supplementation to every 3-d improved forage intake and utilization similar to daily supplementation when provided at medium (240 mg N/kg BW) or high (360 mg N/kg BW) levels. Improved efficiency of nitrogen recycling likely buffered disruptions in protein supply, maintaining intake and digestibility of low-quality forage without daily supplementation. Supplementation of protein every 3 d at 240 g N/kg BW appears to the most biologically effective strategy, increasing intake of LQF and maximizing OM digestibility and N utilization.

Forage productivity and chemical composition of Megathyrsus maximus cv. Tamani under defoliations regimes

The effects of defoliation frequency (21, 28, 35 and 42 days) and defoliation intensity (20, 30 and 40 cm above the ground) on green dry matter (GDM) yield, and chemical composition of Megathyrsus maximus cv. Tamani were evaluated under natural field conditions at the Roraima´s savannas. Defoliation regimes affect productivity and chemical composition of M. maximus cv. Tamani forage. The decrease in the pasture defoliation frequency and intensity improved the accumulation of forage, however it reduces the tissue concentrations of N, P, Ca, Mg and K. Irrespective of defoliation frequencies, the highest levels of N (25.31 g kg-1), P (2.11 g kg-1), Mg (2.78 g kg-1) and K (21.13 g kg-1) were recorded for the defoliation intensity at 40 cm above the ground, except for Ca (4.31 g kg-1), where the greatest concentration was obtained with defoliations at 30 cm above the ground. The use of defoliation frequency around 32 days and defoliation intensity of 28 cm above the ground can be considered adequate for the management of pastures of M. maximus cv. Tamani, in order to provides higher forage productivity and quality, regrowth vigor, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing.

Temporal Changes in Association Patterns of Cattle Grazing at Two Stocking Densities in a Central Arizona Rangeland

Proper grazing management of arid and semi-arid rangelands requires experienced personnel and monitoring. Applications of GPS tracking and sensor technologies could help ranchers identify livestock well-being and grazing management issues so that they can promptly respond. The objective of this case study was to evaluate temporal changes in cattle association patterns using global positioning system (GPS) tracking in pastures with different stocking densities (low stocking density [LSD] = 0.123 animals ha−1, high stocking density [HSD] = 0.417 animals ha−1) at a ranch near Prescott, Arizona. Both pastures contained similar herd sizes (135 and 130 cows, respectively). A total of 32 cows in the HSD herd and 29 cows in the LSD herd were tracked using GPS collars at location fixes of 30 min during a 6-week trial in the summer of 2019. A half-weight index (HWI) value was calculated for each pair of GPS-tracked cattle (i.e., dyads) to determine the proportion of time that cattle were within 75 m and 500 m of each other. Forage mass of both pastures were relatively similar at the beginning of the study and forage utilization increased from 5 to 24% in the HSD pasture and increased from 10 to 20% in the LSD pasture. Cattle in both pastures exhibited relatively low mean association values (HWI < 0.25) at both spatial scales. Near the end of the study, cattle began to disperse likely in search of forages (p < 0.01) and travelled farther (p < 0.01) from water than during earlier periods. Real-time GPS tracking has the potential to remotely detect changes in animal spatial association (e.g., HWI), and identify when cows disperse, likely searching for forage.

Forage productivity and chemical composition of Panicum maximum cv. Mombaça under defoliations intensities and frequencies

The effects of defoliation frequency (28, 35, 42 and 49 days) and defoliation intensity (30, 40 and 50 cm above the ground) on green dry matter (GDM) yield, and chemical composition of Panicum maximum cv. Mombaça were evaluated under natural field conditions at the Roraima´s savannas. Defoliation regimes affect productivity and chemical composition of grass forage. The decrease in the pasture defoliation frequency and intensity improved the accumulation of forage, however it reduces the tissue concentrations of N, P, Ca, Mg and K. Irrespective of defoliation frequencies, the highest levels of N (23.99 g kg-1), P (2.12 g kg-1), Ca (4.22 g kg-1), Mg (2.87 g kg-1) and K (21.45 g kg-1) were recorded for the defoliation intensity at 40 cm above the ground. The use of defoliation frequency around 42 days and defoliation intensity of 42,9 cm above the ground can be considered adequate for the management of pastures of P. maximum cv. Mombaça, in order to provides higher forage productivity and quality, regrowth vigor, larger efficiency of forage utilization, greater tissue renewal and canopy structure more favorable to grazing.

The use of an impeller mowing conditioner during haymaking had no effects on feeding behavior, feed intake or performance of organic dairy cows

Impeller mowing conditioners are commonly used to speed up the drying process on the field, making forage preservation (haying, ensiling) less dependent on weather conditions. However, the effects of this technique on the nutritive value of the forage and dairy cows' responses have not been investigated yet. Each half of two fields of grass-dominated swards, first regrowth, was cut either with or without the use of an impeller mowing conditioner (experimental hay and control hay, respectively). Ceteris paribus conditions were guaranteed by the same cutting and wilting times (roughly 48 h), number of teddings, field pickup technique and barn-drying method. At the beginning of the feeding trial, 19 lactating Holstein cows were allocated to one of two groups, one control (nine cows) and one experimental group (10 cows) and were fed the respective forage plus a fixed amount of concentrate [3.6 kg d−1; dry matter (DM) basis]. After a 14-d adaptation period, data were collected over 21 consecutive days. Covariate data of cows were collected prior to the experimental feeding period, over a time span of 9 d, and included in the statistical model. Results revealed that control and experimental hay showed significant (P < 0.05) differences in the nutrient profile. However, the magnitude of these differences was not enough to affect intakes of hay (18.4 ± 0.29 kg DM d−1), total dietary energy or chewing activity, but did lead to a decreased intake of water-soluble carbohydrates and an increased crude protein intake, thus affecting ruminal nitrogen balance (P < 0.01). This resulted in a higher milk urea content [23.3 vs 17.9 mg (100 mL)−1; P < 0.01] in cows fed the experimental hay, whereas other milk performance parameters remained unaffected. In conclusion, the use of the impeller mowing conditioner did not affect the overall forage utilization by cows when the diet contained about 16% concentrate (DM basis). As this is the first study dealing with the effects of an impeller mowing conditioner on cows' responses, future research should consider investigating the effects of mowing conditioners when cows are fed only forage or diets with lower concentrate amounts.

Factors Affecting Sugar Accumulation and Fluxes in Warm- and Cool-Season Forages Grown in a Silvopastoral System

Forage management and environmental conditions affect water soluble carbohydrate (WSC) storage, and, in turn, influence ruminant forage utilization in silvopastoral systems. The objective was to determine effects of four dependent variables: forage species [(non-native, C3 (orchardgrass (Dactylis glomerata L.)) and native C4 mix (8:1:1 big bluestem (Andropogon gerardii Vitman), little bluestem (Schizachyrium scoparium Michx. Nash) and indiangrass (Sorghastrum nutans L.))]; fertility (poultry litter and an unfertilized control); forage sampling date (mid-May, late-May, early-June, mid-June, and late-June); and hour of day (0800, 1100, 1400, and 1700 h) on WSC accumulation in a silvopasture. Concentrations of WSC (g kg DM−1) were greater (p ≤ 0.05) for C3 forages, with poultry litter not impacting WSC accumulation. Overall, WSC was greatest in mid-June, with the lowest WSC concentration observed at 0800 compared to 1100, 1400, and 1700 h (p ≤ 0.05). Therefore, harvesting forages later in the day resulted in greater WSC. A stepwise regression model indicated acid detergent fiber, ash, and forage P concentration were the best predictors (R2 = 0.85, p ≤ 0.05) of forage WSC. These results may be useful in future studies aimed at explaining diurnal cattle grazing preference and optimum forage harvest timing in silvopastoral systems.

Experiment and Optimization of High-Efficiency Mechanical Separation of Peanut Seedlings and Residual Film Based on Suspension Velocity

HighlightsAn efficient method for separating peanut seedlings and residual film harvested from film-mulched peanut was proposed, and the mechanism was optimized.The relationships between the suspension velocity and moisture content of different shredded materials were studied.Four-factor, three-level Box-Behnken experiments were carried out and analyzed, and the optimal parameter combination was determined.A validation test was carried out to verify the rationality and accuracy of the optimized regression model.Abstract. To address the problems of lower residual film removal and higher material loss in the forage utilization of peanut seedlings wrapped in residual film, this study explored the relationships between the suspension velocity and moisture content of different shredded materials derived from peanut seedlings and conducted performance tests and parameter optimization for a machine that uses peanut seedlings as forage material. Four-factor, three-level Box-Behnken experiments were designed using the rotational speeds of the shredding shaft, upper fans, and lower fans and the frequency of the vibrating sieve as test factors, and using the residual film removal rate and material loss rate as response values. The test results indicated that the suspension velocity of the shredded materials showed a quadratic relationship with moisture content. The performance tests showed that the significance sequence of the test factors for the residual film removal rate was: rotational speed of the lower fans, rotational speed of the upper fans, rotational speed of the shredding shaft, and frequency of the vibrating sieve. The significance sequence for the material loss rate was: rotational speed of the lower fans, rotational speed of the shredding shaft, frequency of the vibrating sieve, and rotational speed of the upper fans. The parameter optimization and validation test showed that the residual film removal rate was 92.71% and the material loss rate was 8.19% when the rotational speeds of the shredding shaft, upper fans, and lower fans were 1650, 770, and 665 rpm, respectively, and the frequency of the vibrating sieve was 4 Hz. The relative errors between the validation test results and the predicted values from the regression models were less than 3%, which suggests that the regression models are reliable. This study provides a reference for the forage utilization of peanut seedlings harvested from film-mulched peanut and provides a reference for determining the optimal working parameters of forage processing machines. Keywords: Agricultural machinery, Box-Behnken experiment, Optimization, Peanut film-seedling separation, Suspension velocity.

Performance of weaner rabbits fed forage supplemented with local spices

Chemical composition of spices revealed that they have the potential to enhance forage utilization by rabbits. A study was conducted to evaluate the performance of weaner rabbits fed forages supplemented with spices (curry, utazi, uziza and scent leaf). This study lasted fo 56 days. Five treatment diets were formulated: diet 1 (control without spice), diet 2 (curry), diet 3, (utazi), diet 4 (uziza) and diet 5 (scent leaf) with the same percentage inclusionrespectively. Thirty weaner rabbits were randomly allocated to the treatment diets with six rabbits per treatment and two per replicate in a Completely Randomized Design. Feed an water were provided to the weaner rabbits ad libitum. There were no significant differences (P>0.05) in the growth parameters except in the feed intake while the organ proportion and carcass cut part of rabbits fed the treatment diets showed significant differences (P<0.05) inall the cut parts measured. However, rabbits fed forage supplemented with curry, utazi, uziza and scent leaf were significantly different (P<0.05) among the treatments in all the organ proportions measured. The spleen of weaner rabbits fed forage supplemented with curry, utazi, uziza and scent leaf were significantly (p<0.5) than that of diet 1 (control) which indicates higher antibody production in the body of rabbits fed diets containing spices to fightagainst any toxin associated with spices since spleen is the major source of lymphocytes responsible for defense. From the findings in this study, it could be concluded that rabbits fed local spices especially curry and utazi did better and therefore are recommended in weaner rabbits diets for better performance.

Grazing Systems to Retain and Redistribute Soil Phosphorus and to Reduce Phosphorus Losses in Runoff

A study of phosphorus accumulation and mobility was conducted in eight pastures in the Georgia piedmont, USA. We compared two potential grazing treatments: strategic-grazing (STR) and continuous-grazing-with-hay-distribution (CHD) from 2015 (Baseline) to 2018 (Post-Treatment) for (1) distribution of Mehlich-1 Phosphorus (M1P) in soil and (2) dissolved reactive phosphorus (DRP) and total Kjeldahl phosphorus (TKP) in runoff water. STR included rotational grazing, excluding erosion vulnerable areas, and cattle-lure management using movable equipment (hay-rings, shades, and waterers). After three years of treatment, M1P had significantly accrued 6- and 5-fold in the 0–5 cm soil layer and by 2- and 1.6-fold in the 5–10 cm layer for CHD and STR, respectively, compared to Baseline M1P. In STR exclusions, M1P also increased to 10 cm depth post-treatment compared to Baseline. During Post-Treatment, TKP runoff concentrations were 21% and 29% lower, for CHD and STR, respectively, in 2018 compared to 2015. Hot Spot Analysis, a spatial clustering tool that utilizes Getis-Ord Gi* statistic, revealed no change in Post-Treatment CHD pastures, while hotspots in STR pastures had moved from low-lying to high-lying areas. Exclusion vegetation retained P and reduced bulk density facilitating vertical transportation of P deeper into the soil, ergo, soil P was less vulnerable to export in runoff, retained in the soil for forage utilization and reduced export of P to aquatic systems