Post-grazing Forage Mass Research Articles

Disponibilidad de forraje en praderas de pasto Xaraés en respuesta a fuentes de nitrógeno convencionales y tratadas con N-(n-butil) triamida tiofosfórica (NBPT)

The N-(n-butyl) thiophosphoric triamide (NBPT), a urease inhibitor, has been reported as one of the most promising compounds to reduce losses by volatilization, and to maximize the use of urea nitrogen (N) in agricultural systems. A field study was carried out to examine urease inhibitors' potential about volumetric density and forage mass grass (Brachiaria brizantha cv. Xaraés) to N application. The experiment was carried out from September 2017 to September 2018. The experimental design used was complete randomized blocks in the 3×2×4 factorial array, considering: three periods of the year (wet season, dry season, and the transition), two sources of urea (conventional urea and NBPT–treated urea), and four N rates (0, 80, 160 and 240 kg N ha-1 yr-1), replicated three times. Nitrogen sources promoted a positive effect (P<0.0001) on bulk density, forage mass, and in the grazing stratum during the wet season and the transition season, with increasing N rates in pastures. The leaf: stem ratio decreased linearly (P<0.0045) as increased N rates, and the higher ratio during the wet season and lower in the dry season of the year. For the rates of 80 kg N ha-1 yr-1, there was a significant difference (P=0.0042) between sources, with greater (P=0.0006) forage mass of 0–30 cm, post-grazing forage mass (P=0.0042) and forage volumetric density (P=0.0006), when utilized the conventional urea. The application of N, regardless of the source, provides an increase in forage mass and volumetric density in Xaraés grass pastures up to a dose of 240 kg N ha-1 yr-1, in the transition season and wet season.

23 Performance of Pregnant Beef Heifers During Spring Rotational Grazing of Novel Endophyte Tall Fescue Following Complete Renovation

Abstract The objective of this study was to analyze animal performance following renovation of toxic-infected tall fescue (TF) to novel endophyte tall fescue (NE) in order to increase producer adoption of NE. In 2018, three renovation strategies were implemented in a randomized complete block design. Strategies included: 1) control (C), 2) renovation to NE after one season of a single-specie cover crop (1-SM), 3) renovation to NE after three seasons of a single-specie cover crop (3-SM), and 4) renovation to NE after three seasons of a multi-specie cover crop (3-CM). Forty-eight pregnant (30-90-d) Angus heifers (initial BW 383 kg ± 32) were randomly assigned to rotationally graze spring growth for 56-d, two years after NE establishment. Pre- and post-grazing forage mass was measured every 7-d. Animal measurements were collected every 14-d. Data were analyzed using procGLIMMIX of SASv9.4. Average daily gain was greatest (P < 0.0001) for cattle grazing 3-CM (0.74 kg/d), 1-SM (0.72 kg/d), and 3-SM (0.62 kg/d) and least for C (0.33 kg/d). Pre-grazing forage biomass was greatest (P = 0.0157) in 3-CM (3261 kg/ha) and lowest in C (2523 kg/ha), with 3-SM (2813 kg/ha) and 1-SM (2779 kg/ha) being intermediate. Post-grazing forage biomass was greatest (P = 0.0063) in 3-CM (1982 kg/ha), C (1916 kg/ha), 1-SM (1900 kg/ha), but lower in 3-SM (1592 kg/ha). Prior to grazing, body condition score (BCS) was higher (P = 0.0029) for animals grazing C (5.48), but change in BCS of animals within treatments was not different (P = 0.798). Hair shedding scores (HS) were not different on d-0, with all treatments near 5. However, HS were highest (P < 0.0001) in C (4.75), and lowest in 1-SM (1.75), 3-SM (2), and 3-CM (2) after 56-d. Data suggest animal performance for NE was improved compared to TF during spring grazing in years following renovation.

Effect of Season and Nitrogen Fertilization on the Agronomic Traits and Efficiency of Piatã Grass in Brazilian Savanna

The aim of the present study was to evaluate the agronomic traits in the pre- and post-grazing and the nitrogen use efficiency of Piatã grass that was subjected to nitrogen fertilization throughout the seasons of the year. The experiment was performed in a randomized block design with four treatments (0, 150, 300, and 450 kg ha−1 N). Grazing was performed with sheep when the forage canopy reached 95% light interception up to 20 cm height of post-grazing. The pre-grazing forage mass of the Piatã grass showed a behavior (p < 0.05) linear to nitrogen fertilization, with higher and lower values in spring and winter, respectively. The post-grazing forage mass responded linearly (p < 0.05) to nitrogen fertilization, with an increase of 43.12% for the dose of 450 kg ha−1 N in relation to pastures without nitrogen fertilization. When the non-fertilized pasture was compared with the highest nitrogen dose, a reduction of 21.79% dead tissue was observed in the post-grazing forage mass. The highest nitrogen use efficiency was obtained with the dose of 450 kg ha−1 N. The forage mass production of the Piatã grass in the pre- and post-grazing conditions are positively influenced by nitrogen fertilization and the seasons of the year, with lower values in winter.

Fixed versus variable rest period effects on herbage accumulation and canopy structure of grazed 'Tifton 85' and 'Jiggs' Bermuda grass

Abstract: The objective of this work was to evaluate the effects of variable and fixed rest periods on the forage production, plant-part composition, and canopy structural characteristics of 'Tifton 85' and 'Jiggs' Bermuda grass (Cynodon spp.) pastures under rotational stocking. The treatments were two grass cultivars (Jiggs and Tifton 85) and two rest periods (grazing starting whenever the canopy reached 25 cm or every 28 days, regardless of canopy height). A completely randomized experimental design, with a 2×2 factorial arrangement (two grass cultivars and two managements), was used with three replicates. The experiment was carried out during the summer growing season in Piracicaba, SP, Brazil. Pre- and post-grazing forage mass chacteristics were evaluated. 'Jiggs' and 'Tifton 85' canopies had similar light interception (96.8%) at pre-grazing, for fixed and variable rest periods; however, they showed different canopy structural characteristics. 'Jiggs' had greater stem proportion, greater canopy height during pre-grazing, and lower leaf area index. There were no differences between strategies and between grass cultivars for total yield, which averaged 16.8 Mg DM ha-1. Fixed and variable rest periods can be used for 'Tifton 85' and 'Jiggs' Bermuda grass.

Efeito da adubação nitrogenada na produção de forragem, teor de proteína bruta e taxa de lotação em pastagens de azevém

O objetivo desta pesquisa foi avaliar a produção e o teor de proteína bruta da forragem de três pastagens de azevém (Lolium multiflorum Lam) cv. Comum, adubadas com 50, 100 e 150 kg de N/ha, na forma de ureia, de maio a outubro de 2012, onde foram conduzidos cinco ciclos de pastejo. Na avaliação da pastagem de azevém foram usadas vacas da raça Holandesa (530 kg PC) que receberam diariamente suplementação alimentar de 4,5 kg de concentrado. Avaliou-se a massa de forragem no pré e no pós-pastejo, a composição botânica e estrutural do azevém, e a taxa de lotação. Foram coletadas amostras de forragem pelo método de simulação de pastejo para análise de proteína bruta. O delineamento experimental foi o inteiramente casualizado com três tratamentos (níveis de N) e três repetições (piquetes). Os valores médios para produção de forragem, teor de proteína bruta e taxa de lotação foram: 4827; 6344 e 6123 kg/ha; 20,17; 21,51 e 22,82%; 2,3; 2,95 e 3,32 UA/ha para os tratamentos de 50, 100 e 150 kg de N/ha, respectivamente. O nível máximo de nitrogênio recomendado é de 100 kg de N/ha.

Effects of post-grazing forage mass on a beef cattle grazing system on Tanzânia grass pastures

The objective of this study was to evaluate the effect of grazing intensity on herbage accumulation, animal performance, and total system yield on irrigated Tanzania grass pastures under rotational stocking. The experiment was conducted from October 1999 to January 2001, in a complete randomized block design with four replications. Treatments consisted of three grazing intensities, represented by the following quantities of green forage dry mass remaining after grazing: 1,000 (high intensity), 2,500 (intermediate intensity) and 4,000 (low intensity) kg ha−1. Grazing cycles were of 36 days (33 rest and 3 grazing). The values observed at the end of the experiment for post grazing forage mass were close to the proposed values. Forage yield was 25,278, 36,850, and 34,144 kg DM ha−1, whereas animal performance was 0.398, 0.541, and 0.564 kg BW day−1for high, intermediate and low intensities, respectively. Grazing intensity was positive related to the stocking rate (6.5, 5.2 and 4.1 AU ha−1 at high, intermediate and low intensities, respectively). Total system yield was not affected by treatments, ranging between 1,518 and 1,287 kg BW ha−1 year−1.

Green leaf allowance and dairy ewe performance grazing on tropical pasture1

The objective of this study was to explain the influence of green leaf allowance levels on the performance of dairy ewes grazing a tropical grass. Seventy-two lactating ewes grazed Aruana guineagrass (Panicum maximum Jacq. cv. Aruana) for 80 d. The treatments were 4 daily levels of green leaf allowance (GLA) on a DM basis corresponding to 4, 7, 10, and 13 kg DM/100 kg BW, which were named low, medium-low, medium-high, and high level, respectively. The experimental design was completely randomized with 3 replications. During the experimental period, 4 grazing cycles were evaluated in a rotational stocking grazing method (4 d of grazing and 16 d of rest). There was a linear effect of GLA on forage mass, and increasing GLA resulted in increased total leaf mass, reaching an asymptotic plateau around the medium-high GLA level. The stem mass increased with increased GLA, and a pronounced increase was observed between medium-high and high GLAs. Increasing GLA increased both forage disappearance rate and postgrazing forage mass. Leaf proportion increased with GLA, peaking at the medium-high level, and the opposite occurred for stem proportions, which reduced until medium-high GLA level, followed by an increase on high GLA. Forage CP decreased linearly with GLA, and increasing GLA from low to high reduced CP content by 31%. On the other hand, NDF increased 14% and ADF increased 26%, both linearly in response to greater GLA levels. Total digestible nutrients decreased linearly by 8% when GLA increased from low to high level. Milk yield increased, peaking at medium-high GLA (1.75 kg ewe(-1) d(-1)) and decreased at high GLA level (1.40 kg ewe(-1) d(-1)). Milk composition was not affected by the GLA levels. There was a reduction in stocking rate from 72 to 43 ewes/ha when GLA increased from low to high level. Productivity (milk yield kg ha(-1) d(-1)) increased as GLA increased, peaking at medium-low level (115 kg ha(-1) d(-1)). Although this tropical grass showed the same pattern in responses to GLA levels as reported in the literature with temperate pastures, the magnitude of the process changed and the maximum response in milk yield from lactating dairy ewes grazing a tropical pasture would be achieved with higher forage allowances than in temperate pastures. Overall, Aruana guineagrass grazed by lactating dairy ewes should be managed to provide 7 to 10 GLA in kg DM/100 kg BW according to the production goals.

Ganho de peso e produtividade animal em capim-marandu sob pastejo rotativo e adubação nitrogenada

O objetivo deste trabalho foi avaliar metas de manejo para capim-marandu (Urochloa brizantha cv. Marandu) submetido a pastejo rotativo e a doses de nitrogênio, de janeiro de 2009 a abril de 2010. Os tratamentos consistiram da combinação de duas frequências de pastejo (altura pré-pastejo de 25 e 35 cm) e de duas doses de fertilizante nitrogenado (50 e 200 kg ha-1 por ano) em delineamento de blocos ao acaso com arranjo fatorial 2x2 e quatro repetições. A altura de pós-pastejo estipulada foi de 15 cm. Maiores valores de ganho de peso médio por animal por dia (0,629 e 0,511 kg dia-1) e por hectare (886 e 674 kg ha-1), bem como de taxa de lotação (3,13 e 2,85 UA ha-1), foram observados nos pastos manejados com altura pré-pastejo de 25 cm. A aplicação de 200 kg ha-1 de N resultou em aumentos na percentagem de folhas na massa de forragem pós-pastejo, nas taxas de acúmulo de forragem, na taxa de lotação e no ganho de peso por área. A mais adequada estratégia de manejo corresponde à altura pré-pastejo de 25 cm, independentemente da dose de nitrogênio utilizada.

Performance and Serum Metabolites of Fall-Weaned Beef Steers Strip-Grazing on Nonstockpiled Tall Fescue

Limited information is available regarding the use of different tall fescue (Festuca arundinacea Schreb.) types during the fall to support the growth of calves after weaning. Seventy-two springborn beef calves were evaluated in 2 consecutive years (36 calves/yr) during a 42-d backgrounding period to determine the effects of weaning and endophyte infection of tall fescue on performance, apparent DMI, percent forage utilization, and serum metabolite concentrations. In each year, 4 calves were assigned to each pasture (n = 3 pastures/treatment) and grazed endophyte-free, toxic endophyte-infected, or non-ergot alkaloid-producing endophyte-infected tall fescue. No effect of tall fescue type (P > 0.10) was detected on apparent DMI, ADG, or serum concentrations of blood urea N, creatine kinase, glucose, and nonesterified fatty acids. Postgrazing forage mass tended (P = 0.07) to be greater for endophyte-infected pastures, and percent forage utilization differed (P = 0.006) between tall fescue types, being lowest for endophyte-infected tall fescue (31.2%). All 3 tall fescue types provided enough forage mass and nutritive value to support BW gains in excess of 1 kg/d in newly weaned beef calves. Creatine kinase peaked on d 1 (P < 0.05) as a result of weaning and transport of the calves. Nonesterified fatty acid and creatine kinase concentrations on d 1 reflected the effect of transport on tissue mobilization. Backgrounding calves during fall on any of the tall fescue types studied allows for acceptable ADG, with no detrimental effects before entering a stocker or finishing program.

Initial Nutritive Value and Utilization Affect Apparent Diet Quality of Grazed Forage

An on-farm study was conducted to measure the effect of forage nutrive value and utilization on diet quality selected by cattle grazing rotationally stocked pastures. In New York 20 paddocks on three farms were grazed by lactating dairy cows or heifers, and in West Virginia 47 paddocks on four farms were grazed by lactating beef cows and calves or yearlings. Most pastures were grazed for one to three days. For each nutritive value component - crude protein (CP), acid detergent fiber (ADF), neutral detergent fiber (NDF), non structural carbohydrates (NSC), and total digestible nutrients (TDN) - apparent diet quality was calculated as the components calculated mass in the pregrazing forage mass minus the calculated mass in the postgrazing forage mass divided by the forage mass disappearing during grazing. Forage utilization was calculated as pregrazing forage mass minus postgrazing forage mass divided by pregrazing forage mass. Cattle grazed selectively increasing CP, NSC, and TDN and decreasing ADF and NDF in the apparent diet compared to the pregrazing forage. Initial pasture nutritive value had the major effect on apparent diet quality. Forage utilization modified apparent intake by reducing the magnitude of selective grazing.

Effects of stocking rate and creep grazing on performance by Spanish and Boer × Spanish does with crossbred Boer kids

Twenty-six Spanish does with twin Boer × Spanish kids and 26 Boer × Spanish does with twin 3/4 Boer–1/4 Spanish kids were used in a 76-day experiment to determine effects of stocking rate (SR) and creep grazing on pre-weaning performance. The study commenced approximately 2 months after kidding. There were four treatments, three involving SR and one creep grazing, with two animal groups or replicates for each treatment (consisting of both genotype sets) per treatment. Groups had 4 does with 8 kids for the low SR (L), 6 does with 12 kids for a moderate SR (M), and 8 does with 16 kids for both the high SR (H) and creep grazing treatment (C). Groups grazed 0.4-ha pastures of various grasses and forbs, with the most prevalent forb being ragweed ( Ambrosia artemisifolia L.). Kids of C groups also had access to similar 0.4-ha pastures that contained the tree legume mimosa ( Albizia julibrissin Durazz). All pastures consisted of four equal size paddocks that were sequentially grazed twice by the same animal groups (i.e., phases 1 and 2 were 48 and 28 days in length, respectively). Post-grazing forage mass decreased linearly with increasing SR ( P < 0.01) (1902, 1454, 928, and 1150 kg/ha; S.E. = 51.2), and change in forage mass during the phases linearly increased ( P < 0.05) (1078, 1247, 1746, and 1493 kg/ha for L, M, H, and C, respectively; S.E. = 120.6). Change (pre-grazing–post-grazing %) during the experiment in the contribution of ragweed to the sward increased linearly with increasing SR ( P < 0.05) (−6, 12, 33, and 9% for L, M, H, and C, respectively; S.E. = 4.5). ADG by does (47, −16, −54, and −2 g/day; S.E. = 21.8) and kids (76, 61, 37, and 81 g/day; S.E. = 6.7) linearly decreased with increasing SR ( P < 0.03); however, kid BW gain per unit land area was similar among treatments (115, 138, 113, and 124 kg/ha for L, M, H, and C, respectively; S.E. = 21.7). Kid ADG was similar between genotypes but doe ADG differed ( P < 0.05) (−47 and 34 g/day for Spanish and Boer × Spanish, respectively; S.E. = 11.5). In conclusion, creep grazing with high SR for does can increase ADG of does and kids but not relative to lower SR for both does and kids. Spanish does with Boer × Spanish kids may be less able to maintain or increase BW while supporting kid growth compared with Boer × Spanish does.