Effect of Native Grassland Intensification over Cattle Performance

The objective was to evaluate the effect of different levels of intensification in native grassland over cattle live weight gain (LWG), stocking rate (SR) and average daily gain (ADG) in Uruguay. The study was carried out in 7.8 ha in Paysandú, between winter 2015 and autumn 2019. Experiment was a randomized complete block design, with 4 replicates. The four treatments applied were native grassland (NG), NG overseeded with Trifolium pratense (6 kg.ha-1) and Lotus tenuis (6 kg.ha-1) + 40 kg.ha-1 of P2O5 (NGO), NG fertilized with 60 kg.ha-1 of N + 40 kg.ha-1 of P2O5 (N60) and NG fertilized with 120 kg.ha-1 of N + 40 kg.ha-1 of P2O5 (N120). Fertilizers used were urea and a blend of 7-40/40-0-4. Animals were growing Holstein steers, with initial live weight of 180 ± 22 kg. Treatments management consisted of rotational stocking system, subdivided in 4 plots, according to blocks. Grazing periods were 14 ±1 day, and rest periods were 45 ±2 days, totaling a grazing cycle of 60 days. The average area of the plots of NG and NGO treatments was 0.72 ha while the treatments of N60 and N120 was 0.26 ha. The SR was significantly different between treatments (P = 0.066). The SR in N60 was 868 ±85 kg LW.ha-1, in N120 was 856 ±124 kg LW.ha-1, in NGO was 583 ±91 kg LW.ha-1 and in NG 544 ±40 kg LW.ha-1. The ADG was not different between treatments (P = 0.372), averaging 0.472 kg LW.animal-1.day-1. The LWG was different between treatments (P = 0.050). The LWG was higher in N60 (432 ±107 kg LW.ha-1.year-1), intermediate in N120 (391 ±91 kg LW.ha-1.year-1) and NGO (306 ±148 kg LW.ha-1.year-1) and lower in NG (206 ±63 kg LW.ha-1.year-1). Increasing levels of intensification in native grassland allow higher ADG and SR, determining higher LWG

Ecosystem and productive benefits of the strategic inclusion of annual legumes into an annual ryegrass pasture in a no-tillage integrated crop-livestock system

Las pasturas anuales de invierno son componentes estratégicos de los sistemas agropecuarios en Uruguay. El objetivo de este estudio fue evaluar el efecto de la fijación biológica de N de leguminosas en una mezcla con raigrás anual en contraste con la adición de fertilizante nitrogenado. El diseño experimental fue un diseño de bloques completos al azar con arreglo factorial 2 x 2 de los tratamientos, con dos tipos de pasturas: a) pastura de raigrás anual (Lolium multiflorum L.), y b) pastura mezcla de raigrás anual con dos especies de leguminosas anuales (Trifolium resupinatum L. y Trifolium vesiculosum L.); y dos niveles de fertilización con N: a) sin fertilizante, y b) 64 kg N ha-1. Las pasturas fueron pastoreadas con novillos Holstein. En verano se realizó un cultivo de Setaria italica para evaluar los efectos de los tratamientos en la producción de biomasa de este. La biomasa acumulada de las pasturas de invierno incrementó significativamente con fertilización de N (P ≤ 0.01), con un incremento de 1277 ± 322.5 kg MS ha-1. La pastura mezcla fertilizada con N produjo un mayor índice de nutrición nitrogenada que la pastura de raigrás anual. La biomasa aérea de raigrás presentó un incremento con el agregado de N; sin embargo, en las pasturas monofíticas de raigrás hubo un aumento del 47% de malezas. La ganancia media diaria de los novillos incrementó con la incorporación de leguminosas, con un promedio en las pasturas mezclas de 1,01 kg PV día-1. La adición de fertilizante nitrogenado permitió una mayor carga animal y una mayor producción animal en invierno. No se encontró un efecto de los tratamientos en la biomasa acumulada de S. italica. La incorporación de leguminosas al raigrás anual permitió una mayor ganancia diaria de peso vivo por animal, pero no produjo un efecto adicional sobre el cultivo sucesor de verano

Configuration of daily grazing and searching of growing beef cattle in grassland: observational study.

Abstract:Many of the studies in Campos grasslands focus on management aspects such as the control of herbage allowance, and application of nutrients and/or overseeding with legumes. However, there is little literature on how the Campos grassland resource is utilised, especially regarding the grazing pattern and the relationship between pasture quantity and quality on daily grazing activities. The study of the ingestive behaviour in species-rich and heterogeneous native grasslands during daylight hours, and understanding how animals prioritise quality or quantity of intake in relation to pasture attributes, are important to comprehend the ingestive-digestive processes modulating the energy intake of animals and to achieve a better grazing management. Therefore, the objective was to describe and quantify the daily grazing behaviour of growing cattle grazing native pasture with different structures as a result of different management practices, and study the relationship of pasture attributes and intake through multivariate analysis. The study was carried out at the Faculty of Agronomy, Paysandú, Uruguay. Treatments were native grassland, overseeding with Trifolium pratense and Lotus tenuis + phosphorus, and native pasture + nitrogen-phosphorus. Grazing activities were discriminated into grazing, searching (defined when animals take 1?2 bites in one feeding station and then change to another feeding station and so on), ruminating and idling. The probability of time allocated to each activity was continuously measured during daylight hours (0700?1930) and was related to pasture structure and forage quality using regression tree models, while the bite rate was determined every 2 h. The diurnal pattern of growing cattle showed grazing and searching sessions, followed by ruminating and idling sessions. The length of sessions (as the probability of time allocated to each activity) varied throughout the day. The grazing probability was greater during afternoon than morning and midday (0.74 vs 0.45 vs 0.46, respectively), and it was associated with higher bite rate (34.2 bites/min). Regression tree models showed different grazing, searching and ruminating strategies according to pasture attributes. During the morning, animals modified grazing, searching, ruminating and idling strategies according to bite rate, crude protein in diet and herbage allowance. At midday, they only adjusted ruminating and idling, while during afternoon sessions, grazing activities were modified by pasture quantity attributes such as herbage mass and herbage allowance. By controlling the herbage allowance, herbage mass and pasture height, animals prioritise quality in the morning and quantity in the afternoon, integrating and modifying the grazing-searching and ruminating-idling pattern