Tiller Population Stability of Aruana Guineagrass Subjected to Cutting Severities and Fertilized with Nitrogen

Tiller appearance, death and survival rates determine the persistency of each grass species and their herbage accumulation. The balance between these factors may vary with frequency and intensity of grazing and nitrogen (N) fertilization. Separated analysis of data on tiller appearance and survival or death may not indicate if tiller population is stable in a given time, that is, if tiller appearance in relation to tiller survival is large enough to maintain tiller population stable. In order to avoid that, an integrated analysis of tiller appearance and death was used, the tiller population stability index (SI), as defined by Bahmani et al. (2003). Aruana Guineagrass (Panicum maximum Jacques cv. Aruana) is widely used as pasture for sheep, which are extremely susceptible to infestation by larvae of gastrointestinal parasites in tropical pasture-based systems. One way to mitigate this problem, reducing the need for the use of anthelmintics, is by managing pastures with post-grazing height low enough to favor the incidence of sunlight at the base of tussocks, killing and controlling larval development, without jeopardizing canopy regrowth and persistence. Sward targets for grazing Aruana Guineagrass correspond to a pre-grazing height of 30 cm, equivalent to 95% canopy light interception during regrowth, and a post-grazing height of 15 cm (Zanini et al. 2012). The objective of this experiment was to evaluate tiller population stability of Aruana Guineagrass subjected to cutting severities and N fertilization using the stability index

Production of Aruana Guinea Grass Submitted to Cutting Severities and Nitrogen Fertilization

Aruana Guineagrass (Panicum maximum Jacques cv. Aruana) is widely used as pasture for sheep, which are extremely susceptible to infestation by larvae of gastrointestinal parasites in tropical pasture-based systems (Zanini et al. 2012) A way to mitigate this problem, and consequently reduce the need for use of anthelmintics, is by managing pastures with post-grazing height low enough to favor the incidence of sunlight at the base of tussocks that will kill and control larval development, without jeopardizing canopy regrowth and persistence. The pre-grazing sward height recommended for Aruana Guineagrass is 30 cm, when the canopy intercepts 95% of the incident light, and a 15 cm post-grazing height (Zanini et al. 2012). As cutting severity and nitrogen (N) fertilization cause morphological and physiological adaptations in individual plants - altering the production of forage grasses - the objective of this study was to evaluate the accumulation of morphological components of Aruana Guineagrass subjected to cutting severities and N fertilization

Evaluation of the Proportion of Botanical and Morphological Components in Forage of Exclusive and Intercropped Grazing Systems

Pasture management that favors ecosystem renewal results from the best botanical proportion of forage. The objective of this work was to evaluate the forage botanical component proportions in macrotiloma (legume) and marandu grass intercropped pasture in comparison with exclusive marandu grass pasture, with or without protein supplementation, using cattle in continuous stocking. The study was carried out at the instituto de zootecnia (nova odessa, sp). Twelve jersey cows (372.83±44.62 kg) were used. Data collection was carried out during periods of 45 in each season, between spring 2019 and winter 2021. The experimental design used was completely randomized blocks, with three treatments and two replications. The experimental treatments were: grass (g): exclusive pasture of urochloa brizantha cv. Marandu; grass + protein supplementation (gp): exclusive pasture of urochloa brizantha cv. Marandu with protein supplementation; and grass + legume (gl): pasture intercropped with urochloa brizantha cv. Marandu and macrotyloma axillare (e. Mey. Verd accession no 279). Forage mass was measured on the 1st, 23rd and 45th days of each experimental period. Forage samples were composed of the representative mass collected at ground level using a gasoline back-mounted brushcutter with a hedge trimmer, at three points, to determined average forage canopy height. The botanical composition was calculated as a percentage of pasture forage mass using the dry weight of the botanical components. Statistical analyses were performed using the sas 9.4 mixed procedure. The data were evaluated by the lsd test and a significant effect was considered when p ≤ 0.05, where the seasons were considered repeated measures in time. The treatments showed statistical difference for dead material proportion (g = 46.37% a, gp = 46.47 % b and gl = 42.11 %b; p < 0.04). Legume proportion was higher in summer (spring = 9.77%b, summer = 30.34%a, autumn = 15.26%b and winter = 5.13%b; p <0.004) and dead material proportion was higher in winter (spring = 48.54%b, summer = 14.23%c, autumn = 38.61%b and winter = 78.55%b; p<0.0001). The proportion of macrotyloma axillare leaves in the forage canopy in this study was 16.60% in summer, 4.87% in spring, 4.48% in autumn and 2.51% in winter, and branches/stalks represented 14.74%a in summer, 4.90 %b in spring, 10.77%b in autumn, and 2.61%b in winter. It can be concluded that botanical maintenance with macrotyloma axillare has potential to be used intercropped with marandu grass, contributing to the system sustainability

Effect of Mixed Pasture of Macrotyloma Axillare and Urochloa Brizantha on Short-Chain Fatty Acid Production in Cattle

Mixed pastures are grazing areas with more than one plant species at the same time, improving the sustainability of production systems. The objective of this study was to evaluate the effects of the intercropping between the legume Macrotyloma and Marandu grass on production of short-chain fatty acids (SCFA) through the ex situ technique of ruminal fermentation. The study was carried out at Instituto de Zootecnia (Nova Odessa, Sao Paulo, Brazil). The experiment followed the guidelines established in accordance with the ethical principles of animal experimentation of the Commission on Ethical Use of Animals of Instituto de Zootecnia (CEUA/APTA/IZ; no. 291-19). Four ruminally cannulated nulliparous Jersey heifers (465.12 kg ± 33.62 kg) in continuous stocking were evaluated. The experimental period was 25 days (12 days of adaptation to the systems, 12 days of dry matter intake (DMI) assessment and one day of ex situ collection) in November 2020 (spring in Brazil). The experiment had in a completely randomized block design. To estimate forage intake, titanium dioxide powder was used as an external indicator of fecal production, and indigestible neutral detergent fiber was the internal indicator. The ex situ technique consisted of collecting rumen samples in flasks, which were incubated in a thermostatic bath to simulate the rumen conditions for 30 minutes. The rumen content was measured during the day at 6 a.m., 10 a.m., 2 p.m. and 6 p.m. (BRT). The experimental treatments were grass (G): exclusive pasture of Urochloa brizantha cv. Marandu and grass + legume (GL): mixed pasture with Urochloa brizantha cv. Marandu and the legume Macrotyloma axillare (E. Mey. Verd, accession NO 279). The chemical characterizations of the forage were: G (DM = 91.63%; CP = 12.11%; ASH = 8.81%; NDF = 59.60% and ADF = 32.10%) and GL (DM = 91.54%; CP = 16.10%; ASH = 9.82%; NDF = 60.44% and ADF = 29.35%). The total forage mass: G = 4329.28kg ha1 and GL = 4733.90kg ha-1. The proportion of botanical components in the forage was: G (grass = 88.80% and dead material = 11.20%) and GL (grass = 62.17%, legume = 25.87% and dead material = 12.87%). Data were analyzed according to PROC MIXED (SAS 9.4). The results obtained were submitted to analysis of variance and submitted to the F-test at 5% probability. The DMI forage was G = 6.10 kg.day-1 and GL = 9.11 kg.day-1; SEM = 0.76 P= 0.10 and the DMI in relation to live body weight was G = 1.37% and GL = 2.11%; SEM = 0.26 P= 0.18). The mixed pasture treatment GL had a higher production of acetic acid (G = 1.99 mol/kg.day-1 and GL = 4.09 mol/kg.day-1; SEM = 0.31 P= 0.04), propionic acid (G = 0.48 mol/kg.day-1 and GL = 1.32 mol/kg.day; SEM = 0. 11 P= 0.03), butyric acid (G = 0.45 mol/kg.day-1 and GL = 1.17 mol/kg.day-1; SEM = 0.08 P= 0.02). The mixed pasture decreased the acetate:propionate ratio (G = 4.13 mol/kg.day-1 and GL = 3.11 mol/kg.day-1; SEM = 0.16 P= 0.04). The use of the ex situ technique generated a large amount of information for SCFA production. The mixed pasture of the legume Macrotyloma and the Marandu grass increased the production of all SCFAs. We concluded that Macrotyloma has potential for use as a feed for ruminants