Rotational Stocking Research Articles

La interfaz suelo-planta en Megathyrsus maximus cv. Mombasa sometida a diferentes dosis de nitrógeno en pastoreo rotacional

This work aimed to evaluate the effects of three nitrogen (N) doses on the morphogenic and structural characteristics, root mass (RM) and distribution in the soil profile, and penetration soil resistance of Mombasa guineagrass pastures managed with rotational stocking. The experimental design used randomized blocks with three N doses (100, 200, and 300 kg ha-1) and three replicates. The criterion for interrupting the pastures’ regrowth was the height of 80 to 90 cm of the canopy (90–95 % of light interception by the canopy). The animals were removed from the paddocks when the canopy reached 50 % of the pre-grazing height. Forage mass and accumulation, canopy morphogenic and structural characteristics, RM and distribution in the soil profile, and soil resistance to penetration were evaluated. In pastures fertilized with 200 and 300 kg ha-1 of N, the highest leaf appearance (0.090 and 0.081 leaves-1 tiller-1 d-1), elongation rates (2.82 and 2.61 cm tiller-1 d-1) and highest daily forage accumulation (113.8 and 106.6 kg ha-1d-1) were observed. Using 300 kg ha-1 of N promoted greater soil resistance to penetration at 10 cm of depth in the post-grazing (3.3 MPa). No effect of N doses was observed for RM (P>0.05). The pre- and post-grazing height control of animals in the paddocks therefore helped to maintain the pasture structure and avoid the soil compaction process. According to the results, it is concluded that 200 and 300 kg ha-1 of N fertilization is a strategy for intensifying pastures.

Biological and economic responses to increasing nitrogen rates in Momba\xe7a guinea grass pastures

Nitrogen fertilization has been recognized as an essential tool towards the establishment of sustainable intensification of pasture-based livestock systems using tropical perennial grasses if, for a given ecosystem it is capable of increasing forage growth, stocking rates and animal performance. This study assessed pasture growth traits, nutritive value, animal and economic responses of Panicum maximum cv. Mombaça guinea grass pastures subjected to different levels of N fertilization (100 (N100), 200 (N200), and 300 (N300) kg N ha−1 yr−1). Pastures were managed under rotational stocking to maintain similar pre (80–90 cm) and post-grazing (45 cm) canopy heights. A partial budget and a Benefit–Cost Analysis were used to assess the economic returns on increasing N fertilization. N300 resulted in greater post-grazing herbage mass. A slightly higher neutral fiber and acid lignin detergent was observed at N100 (P < 0.05); crude protein increased linearly, and in vitro digestible organic matter reached maximum value at 265.4 kg N ha−1 yr−1. Annual averages of animal weight gain were 515, 590 and 660 g d−1, respectively, for N100, N200 and N300. There was a decrease from 3.7 to 1.9 kg of body weight gain per kg of additional N applied when increasing N rates from 100 to 200 and from 100 to 300 kg ha−1. The net profit improved with increasing N levels, but at reducing rates, reaching its maximum at the N300 level. The change from 100 to 200 kg N ha−1 presented the best return, with USD 3.73 for each additional dollar invested, while the change from 200 kg N ha−1 to 300 kg N ha−1 was economically less than optimal, recouping only USD 1.60 for each dollar. The N300 rate presented the highest net profit per hectare (accounting profit), even in a pessimist scenario (25% reduction in production). Despite being profitable, the N300 rate was less than optimal from an economic standpoint, since an additional 100 kg of Nitrogen ha−1 to change from N200 to N300 level reduced both the net returns and the Benefit–Cost ratio. Our results suggest that the economically optimal level of N fertilization for Mombaça guinea grass pasture should be between 200 and 300 kg ha−1.

Effect of mineral-energy supplementation on the performance of young bulls from different genetic groups on pasture

The aim of this study was to evaluate the performance of young bulls from three genetic groups, ½ Brangus x ½ Nellore (BRN), Nellore (NEL) and ½ Canchim x ½ Nellore (CAN), reared on pasture and supplemented with mineral (MS) or energy-mineral (MES) supplement. Eighty-one bulls, with a mean age of 12 months and mean body weight of 252 ± 33 kg were used. The experiment was conducted in a 3x2 factorial completely randomized design. Each genetic group was subdivided into six experimental plots, three received MS and three received MES. Animals were managed in a rotational stocking system in a Tifton 85 grass pasture. The consumption of MS was similar between the genetic groups with an average of 0.073 kg animal-1 day-1, whereas the consumption of MES was higher for BRN, 2.10 kg animal-1 day-1, followed by CAN, with 1.57 kg animal-1 day-1, and lower for NEL, with 1.28 kg animal-1 day-1. The average daily weight gain (ADG) was greater for animals that received MES compared to those that were given MS. For animals that received MS, the BRN group had ADG of 0.64 kg animal-1, while the NEL and CAN groups were similar with a mean of 0.46 kg animal-1. For animals that received MES, the CAN group had higher ADG, 0.97 kg animal-1, while the NEL and BRN groups were similar, with an average of 0.86 kg animal-1. Blood levels of total protein, albumin, creatinine, glucose and cholesterol did not change depending on the types of supplements used or between genetic groups. Higher serum urea levels were observed in NEL and CAN animals that received MS. Serum aspartate aminotransferase levels were higher in BRN and CAN animals that received MES. Gains in rump height, height at the withers, body length, rump width and chest perimeter were greater in animals that received MES. Mostly, the gains in morphometric measurements were greater for crossbred animals than for the NEL group. The supply of mineral-energy supplement in Tifton 85 grass pasture during the rainy season is recommended only for Nellore and ½ Canchim x ½ Nellore young bulls. Crossbred young bulls show greater gains in morphometric measurements than Nellore young bulls during rearing.

Effect of pre-grazing herbage mass on pasture production and performance of suckler-bred steers during the grazing season and subsequent indoor finishing period

The objective was to determine the effect of pre-grazing herbage mass (PGHM) on herbage production and nutritive value, intake and growth of suckler-bred steers in a rotational stocking system, and the residual effects on intake, growth and carcass traits during subsequent indoor finishing. A total of 108 yearling steers previously offered grass silage indoors over 105 days were assigned to one of two PGHM (1500 – low (L) or 2000 – high (H) kg dry matter (DM)/ha; > 4 cm) treatments. Steers (ca. 345 kg at turnout to pasture in spring) rotationally grazed perennial ryegrass (Lolium perenne) dominant pasture in 12 groups of 9 for 203 days. At the end of the grazing season they were housed indoors and offered either (1) grass silage only or (2) grass silage + 3.17 kg concentrate DM/head daily for 136 days until slaughter at 24 months of age. Annual herbage production was higher (8427 vs. 7542 kg DM/ha, P < 0.01) for H than L, but there was no difference between treatments in surplus herbage removed as silage due to the tendency for H steers to consume more herbage/ha while grazing (7363 vs. 6479 kg DM/ha, P = 0.08). During the grazing season, compared to L, steers grazing H had a greater estimated herbage DM intake (6.59 vs. 5.93 kg DM/ha, P < 0.001), daily live weight gain (0.81 vs. 0.76 kg, P < 0.01), live weight at the end of the grazing season (553 vs. 539 kg, P < 0.01) and live weight gain/ha (1261 vs. 1206 kg/ha). During the indoor finishing period there was no PGHM × finishing diet interaction, and no residual effect of PGHM on daily live weight gain, but carcass weight tended to be heavier for H (359 vs. 354 kg, P = 0.06) than L. Compared to silage only, the silage + concentrates group had a higher (P < 0.001) total DM and energy intake, feed conversion efficiency, live weight gain, carcass weight and carcass conformation and fat score. In conclusion, grazing the lower PGHM reduced herbage production, steer live weight gain at pasture, overall live weight gain/ha and tended to reduce carcass weight; therefore, under the conditions of this experiment grazing a PGHM of 2000 kg DM/ha is recommended. Removing concentrates from the finishing diet reduced carcass weight and fatness, making it more difficult to finish steers at a commercially acceptable carcass (carcass fat score > 6.0, 1 - 15 scale).

Sward structure and forage intake rate of elephant grass cv. Napier subjected to strategies of intermittent stocking management

Context Grazing management strategies affect sward structure, changing patterns of foraging and intake, and consequently animal performance. Aims The objective of this study was to evaluate the relationship between sward structure and forage intake rate by cattle grazing elephant grass (Pennisetum purpureum Schumach) cv. Napier subjected to strategies of rotational stocking management. Methods The experiment was conducted in Piracicaba, SP, Brazil, from January 2011 to April 2012. Treatments corresponded to all combinations between two post-grazing conditions (post-grazing heights of 35 and 45 cm) and two pre-grazing conditions (95% and maximum canopy light interception during regrowth; LI). The response variables evaluated at both pre- and post-grazing conditions were: (1) vertical distribution of morphological components; (2) bite rate; (3) bite mass; (4) intake rate; and (5) forage nutritive value (morphological and chemical composition of oesophageal extrusa samples). Key results Bite mass was smaller and bite rate was greater for LI95% swards at pre- and post-grazing, resulting in greater rate of forage intake. The post-grazing height targets affected the morphological and the chemical composition of the forage consumed. Conclusions In general, pastures managed with targets LI95% (pre-grazing) and 45 cm (post-grazing height) resulted in greater leaf percentage and nutritive value of the consumed forage. Implications Adequate grazing management strategies allow for high residual leaf area in pastures, ensuring rapid recovery after grazing. For grazing elephant grass cv. Napier, this corresponded to the combination between the LI95% pre-grazing target and the 45 cm post-grazing height.

O método de pastoreio rotativo “ponta” e “rapador” pode moldar a estrutura das pastagens naturais para aumentar a produção de bovinos de corte?

ABSTRACT: This study evaluated the structure of vegetation and the performance of rearing heifers and cull cows in Campos grasslands managed in the rotational stocking method with first-last stocking in the spring-summer period. The treatments were different rest intervals of 402 and 252 degrees-day, which favor the growth of different functional groups of grasses. A completely randomized block design with two treatments and three repetitions was used. The test animals were 24 heifers in the “first” group and 24 cows in the “last” group. In the stratum between tussock grasses, sward heights greater than 0.16 m were predominant in both treatments, it was 1.3 times more frequent in the 402 DD treatment compared to the 252 DD treatment. Average stocking rate was 22% higher in the 252 DD treatment. Although, no differences were observed for the average daily gain of heifers (0.227 kg.day-1) and cows (0.336 kg.day-1) between treatments, the weight gain per area in the experimental period was greater in the 252 DD treatment. Despite the management system with first and last stoking does not provide significant changes in the structure of the pasture, it allowed to achieve satisfactory performance goals in areas of Campos grassland.

How Biodiversity-Friendly Is Regenerative Grazing?

Regenerative grazing management (ReGM) seeks to mimic natural grazing dynamics to restore degraded soils and the ecological processes underpinning sustainable livestock production while enhancing biodiversity. Regenerative grazing, including holistic planned grazing and related methods, is an adaptive, rotational stocking approach in which dense livestock herds are rotated rapidly through multiple paddocks in short bouts of grazing to defoliate plants evenly and infrequently, interspersed with long recovery periods to boost regrowth. The concentrated “hoof action” of herds in ReGM is regarded vital for regenerating soils and ecosystem services. Evidence (from 58 studies) that ReGM benefits biodiversity is reviewed. Soils enriched by ReGM have increased microbial bioactivity, higher fungal:bacteria biomass, greater functional diversity, and richer microarthropods and macrofauna communities. Vegetation responds inconsistently, with increased, neutral, or decreased total plant diversity, richness of forage grasses and invasive species under ReGM: grasses tend to be favored but shrubs and forbs can be depleted by the mechanical action of hooves. Trampling also reduces numerous arthropods by altering vegetation structure, but creates favorable habitat and food for a few taxa, such as dung beetles. Similarly, grazing-induced structural changes benefit some birds (for foraging, nest sites) while heavy stocking during winter and droughts reduces food for seedeaters and songbirds. With herding and no fences, wildlife (herbivores and predators) thrives on nutritious regrowth while having access to large undisturbed areas. It is concluded that ReGM does not universally promote biodiversity but can be adapted to provide greater landscape habitat heterogeneity suitable to a wider range of biota.

Herbage allowance and stocking method effect on grazing systems: Results of a long‐term experiment

AbstractSward management is critical for animal performance in pastoral environments. We evaluated the performance of sheep grazing Italian ryegrass pastures under factorial combinations of two stocking methods (SM) (continuous and rotational) and two herbage allowances (HA) (10% and 20% of LWT) over 9 years. Average daily gain (ADG) was greater in continuous than in rotational stocking (p &lt; .001) and in HA‐20% when compared with HA‐10% (p = .002). Weight gain per hectare was greater in HA‐10% than HA‐20% (p &lt; .001). HA and total herbage production were the most important factors determining live weight (LW) gain per hectare, whilst sheep ADG relies upon sward parameters (i.e., sward height). Moreover, to increase sheep LW production per hectare in grazing systems, the amount of herbage production and its availability to animals is more important than the SM. These outcomes provide the basis to build sound grazing systems through the optimization of sward management.

Validating a Simple Mechanistic Model That Describes Weather Impact on Pasture Growth.

Mathematical models have many uses. When input data is limited, simple models are required. This occurs in pasture agriculture when managers typically only have access to temperature and rainfall values. A simple pasture growth model was developed that requires only latitude and daily maximum and minimum temperature and rainfall. The accuracy of the model was validated using ten site-years of measured pasture growth at a site under continuous stocking where management controlled the height of grazing (HOG) and a site under rotational stocking at a West Virginia University farm (WVU). Relative forage growth, expressed as a fraction of maximum growth observed at the sites, was reasonably accurate. At the HOG site constant bias in relative growth was not different from zero. There was a year effect due to the weather station used for predicting growth at HOG being 1.8 km from the pasture. However, the error was only about 10-percent. At the WVU site constant bias for relative growth was not different from zero and year effect was eliminated when adjusted for nitrogen status of the treatments. This simple model described relative pasture growth within 10-percent of average for a given site, environment, and management using only daily weather inputs that are readily available. Using predictions of climate change impact on temperature and rainfall frequency and intensity this model can be used to predict the impact on pasture growth.

How canopy structural and morphological characteristics, and forage chemical composition affect a pasture-based dairy system?

Pasture-based systems are prevalent among small-scale family farms. Many farmers consider that the nutritional value of the plant is more relevant than the canopy structure. This study aimed to analyze the various factors related to plant structure and chemical composition that most influence milk yield per hectare under rotational stocking. The experiment was performed at the Animal Husbandry Experimental Station of the Extreme South of Bahia. Three rotational stocking systems with three forage species [Cynodon dactylon (L.) Pers. cv. Tifton 85, Urochloa brizantha (Hochst. ex A. Rich.) Stapf. cv. Xaraés, and Megathyrsus maximus Jacq. cv. Mombasa] were evaluated. Nine crossbred Holstein x Gyr cows were allocated to a balanced 3 x 3 Latin square design. The cows were rotated in three pastures every 14 days. The experimental period consisted of seven evaluation cycles of 42 days each. Cluster analysis, principal component analysis (PCA), and multivariate linear regression were the statistical techniques used to evaluate plant structure and morphological characteristics, and animal performance. Xaraés palisadegrass and Mombasa guinea grass were similar for all evaluated characteristics (P &gt; 0.05), whereas Tifton 85 was different from them in terms of structural, morphological, and chemical composition characteristics (P &lt; 0.05). In the PCA, 59.1% of the total variance was explained by components 1 and 2 for the structural and morphological characteristics, and forage chemical composition. Forage structural and morphological variables showed better results in the multivariate linear regression analysis for milk yield per hectare. Structural and morphological characteristics were more correlated with Mombasa guinea grass than Xaraés palisadegrass and Tifton 85. The structural and morphological characteristics of forages were the main factors determining milk yield per hectare in exclusively pasture-based systems with animals of low production.

Herbage accumulation and tillering dynamics of ‘Zuri’ guineagrass under rotational stocking

AbstractUnderstanding the effects of grazing management on tillering dynamics of forage grasses may help identify management practices that optimize pasture production, stability, and ultimately, persistence. The objective of this research was to evaluate the effects of two grazing frequencies (regrowth interrupted when the canopy was 70 cm tall or at 95% canopy light interception [LI]) and two grazing intensities (reduction of 29 [lenient] or 57% [standard] of initial canopy height) in ‘BRS Zuri’ guineagrass [Megathyrsus maximus (Jacq.) B.K. Simon &amp; S. W. L Jacobs (syn. Panicum maximum Jacq.)], under rotational stocking and on herbage accumulation rate (HAR), tiller appearance rate, tiller mortality, tiller survival rate, tiller stability index (SI), tiller population density (TPD), tiller mass (TM), apical meristem height, and tiller half‐life during two summer rainy seasons in Piracicaba, Brazil. The experimental design was randomized complete block, with a 2 × 2 factorial arrangement. The HAR was not affected by treatments in the first year, averaging 100 kg dry matter ha−1 d−1, but was greater under lenient than standard grazing (146 and 81 kg dry matter ha−1 d−1, respectively) in the second year. In both years, there were no treatment effects on TPD and TM. The use of 95% LI associated with standard defoliation increased the variability in SI. Great tiller population renewal indicated by short tiller half‐life, varying from 31 to 75 d, classifies Zuri as an exploitative cultivar. Zuri guineagrass maintained tiller SI under the grazing treatments imposed but had greater HAR under lenient grazing.

Management of Aries and Aruana Guinea grass cultivars under rotational stocking based on canopy light interception

AbstractEfforts were made to obtain forage cultivars with high production capacity and quality and to determine the ideal time to start animal grazing, respecting the morphological characteristics of the grasses. For this purpose, the nutritional value, digestibility and characteristics of the forage canopy of Aries and Aruana (Megathyrsus maximus (Jacq.) or Panicum maximum) cultivars kept under rotational stocking with sheep were evaluated and the management height was determined based on 95% light interception (LI). The experiment was evaluated with repeated measures over time (grazing cycles by season, in 2 years) with a treatment factor (grass cultivar) in a completely randomized block design with eight replicates, using 800 m2 paddocks. The height of the forage canopy before grazing (pre-grazing) determined by 95% LI stabilized around 29 cm. The highest proportion of Aruana leaf blades was observed in winter. Aries grass presented similar leaf blade percentages in summer, autumn and spring. Similar forage accumulation (FA) was observed for both cultivars, decreasing in spring, autumn and winter. Higher crude protein and in vitro dry matter digestibility (IVDMD) were seen in Aries grass, while Aruana grass presented higher neutral and acid detergent fibre and cellulose and lower IVDMD. The nutritional quality of the grasses was maintained throughout the year. The height of the forage canopy of Aries and Aruana recommended for entry into the paddock is 29 cm to maintain nutritional quality. The successful management strategy adopted for grasses combined with nitrogen fertilization provided a greater forage mass quality.

Low-Intensity, High-Frequency Grazing Positively Affects Defoliating Behavior, Nutrient Intake and Blood Indicators of Nutrition and Stress in Sheep.

The intensity and frequency of grazing affect the defoliating strategy of ruminants, their daily nutrient intake, thus nutrition and physiological status. Italian ryegrass (Lolium multiflorum Lam.) pastures were grazed by sheep either under a low-intensity/high-frequency grazing strategy (Rotatinuous stocking; RN) with nominal pre- and post-grazing sward heights of 18 and 11 cm, respectively, or under a high-intensity/low-frequency strategy (traditional rotational stocking; RT) with nominal pre- and post-grazing sward heights of 25 and 5 cm, respectively. Treatments were arranged under a complete randomized design and evaluated over two periods, in different years. In 2017, the aim was to depict the type of bites that sheep perform during the grazing-down and associate them to the grazing management strategy according to their relative contribution to the diet ingested. In 2018 we estimated the total nutrient intake and evaluated blood indicators of the nutritional status and immune response to stress of sheep. The bite types accounting the most for the diet ingested by RN sheep were those performed on the “top stratum” of plants with around 20, 15, and 25 cm, whereas the type of bites accounting the most for the diet of RT sheep were those performed on “grazed plants” with around 10, 5, and ≤ 3 cm. In 2018, the RN sheep increased by 18% the total organic matter (OM) intake and by 20–25% the intake of soluble nutrients (i.e., crude protein, total soluble sugars, crude fat), digestible OM and of metabolizable energy, and had 17.5, 18, and 6.1% greater blood concentration of glucose, urea nitrogen (BUN) and albumin, respectively, but 17% lower blood neutrophil-to-lymphocyte (N:L) ratio. Sheep grazing vegetative Italian ryegrass pastures under the low-intensity/high-frequency grazing strategy (RN) ingested a diet of better quality from bites allocated on the top stratum of plants, had greater intake of soluble nutrients and blood parameters positively associated with nutritional status and immune response to stress.

Performance of crossbred Holstein x Gyr dairy cows, with and without energy supplementation, in BRS Kurumi elephant grass pastures

This study evaluated the effect of energy supplementation with ground corn on the performance of crossbred dairy cows in BRS Kurumi elephant grass pastures managed under rotational stocking during the rainy season. Six Holstein × Gyr cows were used, with average milk production, body weight, body condition score, and days in milk of 18.0±2.89 kg day−1, 560±66 kg, 2.50±0.21, and 99±12, respectively. The experimental design used was the complete reversion (switchback), and the evaluations were conducted over three grazing cycles, with adaptation periods of 14 days and six days of sample collection. The concentrate supplement (ground corn) was supplied twice a day, at a rate of 2 kg cow−1 day−1 in the morning and 1 kg cow−1 day−1 in the afternoon (as-fed basis). A reduction of 23.4% was observed in the pasture dry matter (DM) intake (PDMI) in cows that received energy supplementation, which corresponds to 2.96 kg day-1 less of PDMI when compared to the group without supplementation. This corresponds to a substitution rate of 1.1 kg of pasture per kg of concentrate consumed (DM basis), which reduced the intake (kg cow−1 day−1) of neutral detergent fiber and crude protein by 18.9% and 13.9% in the cows that received ground corn. There were increases of 11.8%, 9.0%, and 10.1%, respectively, in the milk yield, the 3.5% fat-corrected milk yield, and the energy-corrected milk yield of the cows that received ground corn. The response to supplementation in kg of milk per kg of DM of concentrate consumed was 0.57, and the milk contents of fat, protein, and lactose did not differ between treatments. The energy supplementation with 3 kg cow−1 day−1 of ground corn resulted in an increase of 11.8% in the milk yield of Holstein × Gyr dairy cows grazed on BRS Kurumi elephant grass, as well as promoted increases in the daily protein, lactose, and total solids yields. In addition, the provision of 3 kg day−1 of ground corn for lactating cows grazing on BRS Kurumi increased the efficiency in the use of dietary nitrogen.

Incorporating Alfalfa into Warm-season Grass Systems in the Southeast

Abstract Bermudagrass is the primary warm season perennial forage crop grown in the Southeast (~20 million acres) for livestock and forage operations. While prominent in the region, bermudagrass requires large amounts of fertility and forage quality is moderate relative to other options. There has been great success and a growing interest in interseeding alfalfa into existing bermudagrass stands in the region. This combination eliminates the need for nitrogen fertilization, increases relative forage quality (RFQ) better meeting the nutritional needs of livestock, and decreases the need for supplemental feed. In recent years, research evaluations have been conducted across the Southeast to evaluate the use of alfalfa when incorporated into warm-season grass forage systems under various management strategies. Three projects conducted from 2016–2020 at the University of Georgia Tifton campus evaluated ‘Bulldog 805’ alfalfa interseeded into Tifton-85 bermudagrass (1) when harvested as baleage, (2) under grazing management and(3) in a clipping study to better define defoliation management recommendations. Overall findings from this work observed that alfalfa-bermudagrass mixtures provide greater seasonal herbage accumulation, extend the growing season by three to four months annually, and increase forage DM digestibility and CP compared to bermudagrass alone. Steers on ABG managed under rotational stocking had greater total gain/ha (~%33 increase) due to a higher stocking density throughout the growing season than a bermudagrass monoculture. Results indicate that interseeding alfalfa into bermudagrass is a viable option for southeastern forage systems and can be an effective way to improve forage quality, extend the grazing season, and reduce the need for additional supplementation when fed to livestock.

Forage mass and canopy structure of Zuri and Quênia guineagrasses pasture under rotational stocking

This work evaluated the productive and structural characteristics of the BRS Zuri and BRS Quênia cultivars under rotational stocking management. The evaluations were divided into five periods according to rainfall regime (high, medium, and low rainfall) during 16 months of the years 2016-2018. Pastures were grazed when canopies intercepted 95% of incident light to stubbles corresponding to 50% of the pre-grazing height. The pre- and post-grazing heights varied as a function of cultivar, with higher values for BRS Zuri [...]

Tall fescue management and environmental influences on soil, surface residue, and forage properties

AbstractEnvironmental characteristics within a region often form site‐specific agro‐ecological responses to management. Using 92 fall‐stockpiled tall fescue [Schedonorus arundinaceus (Schreb.) Dumort.] field trials in North Carolina and surrounding states, our objective was to test the influence of two management factors (forage utilization and pasture age) and two environmental factors (elevation and soil textural gradients) on soil properties at 0‐to‐10‐cm depth, surface residue carbon (C) and nitrogen (N) contents, and absolute forage mass and nutritive values and their responses to N fertilization. Soil organic C and N fractions (i.e., total, particulate, and mineralizable) were greater (a) with improved (rotational stocking) than conventional (haying and/or continuous grazing) forage utilization, (b) in older pastures, (c) at higher elevation, and (d) with finer texture. Soil chemical properties were variably affected by these factors, and soil‐test P was not affected. Surface residue N tended to be greater with improved than conventional forage utilization, but surface residue C was not affected by any of the factors. Crude protein was greater and dry matter yield response to N fertilizer was lower with improved than with conventional forage utilization. Forage mass was lower and nutritive values were greater at higher elevation. Soil organic C and total soil N sequestration rates during a 25‐yr period were 0.75 Mg C ha−1 yr−1 and 75 kg N ha−1 yr−1, respectively. Elevation and soil texture imparted strong environmental controls on a diversity of soil properties, but management factors mostly affected surface‐soil organic C and N fractions, which helped sustain forage productivity and nutritive value with lower N fertilizer input.

‘Rotatinuous’ stocking: An innovation in grazing management to foster both herbage and animal production

‘Rotatinuous’ stocking is a grazing management strategy based on animal behavioural responses to sward structure which is designed to maximize herbage intake per unit of grazing time. It is an alternative to traditional grazing management practices focusing on pasture use efficiency and maximizing herbage accumulation and harvesting. To investigate this approach, Italian ryegrass (Lolium multiflorum) pastures grazed by sheep were evaluated in 2014 and 2015 under two contrasting grazing management strategies. Paddocks were distributed under a complete randomized block design with four replicates. Grazing management strategies were: traditional rotational stocking (RT), with pre- and post-grazing sward heights of 25 and 5 cm, respectively, and ‘Rotatinuous’ stocking (RN), with pre- and post-grazing sward heights of 18 and 11 cm, respectively. Thirty-two castrated Texel × Polwarth crossbred lambs were randomly allocated to treatments. As a consequence of grazing strategies, the stocking cycles were 12 and 4, with resting periods of 13 and 35 days, respectively, for RN and RT treatments. Herbage production, total herbage harvested, and feed conversion efficiency were 28%, 20%, and 40%, respectively, greater for RN than for RT treatment. Although the stocking rate was lower, the average daily gain per animal and live weigh gain per hectare were 153% and 43%, respectively, greater for the RN treatment. Despite the RN treatment being orientated to maximize herbage intake per unit of grazing time, it results in greater total herbage production and harvesting. We conclude that the ‘Rotatinuous’ stocking strategy is not necessarily reversed by low herbage harvesting efficiency. This innovation in grazing management conciliates high herbage and animal production at the same time.

Soil nutrient distribution on cattle farms in three physiographic regions of North Carolina

AbstractBeef cattle production systems are sometimes considered a source of nutrient enrichment due to alteration of botanical composition and excretion of nutrients in isolated zones of pastures. However, research on environmental effects from livestock grazing in the eastern United States has been scant. We conducted an intensive soil sampling campaign on six private farms in three physiographic regions of North Carolina to determine the impacts of landscape features, pasture management, and animal behavior on a suite of soil nutrients. Total and particulate organic C and soil‐test biological activity (STBA) increased with increasing elevation due to edaphic and climate factors. Within farms, fields with different management illustrated that: (a) swine and poultry manure application can favorably enrich soil with infrequent application, but lead to excessive soil‐test P and K with repeated application; (b) positive impacts on total and particulate organic C and STBA occur with grazed perennial forages compared with annual forages and previous cropping; and (c) enrichment of total and particulate organic C and STBA occurs with winter hay feeding, but excessive nutrient accumulation can occur if fed in the same location repeatedly. Aggregated enrichment of soil organic C, STBA, and soil‐test P and K occurred on 30% of fields near drinking water tanks, shade sources, gates, and hay feeding stations. Improved grazing management with rotational stocking and more year‐round grazing helped to minimize occurrence and magnitude of nutrient enrichment zones. We conclude that improved grazing management systems can have positive impacts on the environment, and likely on farm livelihoods.

Physiological and behavioural responses of sheep grazing in a tropical silvopastoral system

Context Integrating trees and pastures can provide benefits to grazing animals in warm climates, such as provision of shade during the excessive heat. Aim Our aim was to evaluate the effects of two arrangements of trees on grass production and behavioural, physiological and blood parameters of crossbred lambs grazing massai grass (Megathyrsus maximus) pastures in a tropical environment in São Paulo state, Brazil. Methods Two groups of 24 Santa Inês × Dorper male lambs (~90 days old, 24.0 ± 3.3 and 22.0 ± 2.4 kg bodyweight, respectively) were used in two growing seasons, stratified by initial bodyweight and randomly assigned to one of three treatments: unshaded massai grass (no shading, NS), moderate shading (MS), or intense shading (IS). Treatments MS and IS were established with single rows of eucalyptus trees at spacing 12 m or 6 m between rows and 2 m within rows, corresponding to 786 and 1190 trees/ha. Each growing season consisted of two grazing cycles of ~20 days each, when tester animals grazed simultaneously in a rotational stocking system with variable stocking rate. Behavioural observations were feeding, lying ruminating, standing ruminating, lying, standing still, searching for food, and other. Physiological measurements were rectal temperature, respiratory frequency and heart rate. Blood parameters included haemogram, acute-phase proteins and serum cortisol concentrations. Key results Animals under treatment IS spent more time (P &lt; 0.05) lying, standing still and at other activities than animals under NS and MS. Moreover, they presented lower rectal temperature and respiratory and heart rates than animals under NS during the first growing season, which was the season with higher temperatures. Cortisol and acute-phase proteins were not affected by treatment. Conclusions When animals were exposed to sun, the silvopastoral system was efficient for avoiding heat stress; however, the density of trees reduced the forage mass. Implications The silvopastoral system is a viable alternative production system in warm climates to improve the welfare of sheep, but the density of trees must be considered so that it does not negatively influence the forage mass.