Jalise Fabíola Tontini

Forage budgeting is a key decision‐support tool in pasture‐based livestock systems. However, its application in subtropical regions remains challenging due to high seasonal variability in forage production and botanical composition. The objective of this study was to investigate and discuss the possibility and constrains of carrying out a forage planning model for cattle and sheep in the subtropical region of Brazil, including the native grasslands of Pampa biome. This study monitored cattle herds and sheep flocks on a commercial farm in Pampa biome over a 1‐year period. Simulations and planning models were carried out based on a New Zealand “Feed Budget” approach. Data were collected from a 96.6‐hectare area, with herbage accumulation rates estimated monthly using grazing exclusion cages. Information on pasture quality, including levels of protein and energy, was estimated from the literature. The results indicate that forage planning based solely on dry matter availability is feasible. However, when planning is conducted according to animal metabolizable energy requirement, adjustments to meet energy demand are not possible due to low forage quality and limitations in animal intake capacity. Although the native grasslands of the Pampa biome produce sufficient total ME per hectare, cattle and sheep are unable to ingest enough energy to meet their requirements because of physical intake constraints. This study identifies different management strategies and highlights the need for further studies to better align forage supply with animal demand under grazing conditions in subtropical regions.

Condensed tannins and α-tocopherol are important antioxidants produced by forage plants, with potential benefits for grassland sustainability and ruminant productivity. The objective of this study was to quantify the concentrations of phenolic compounds in Desmodium incanum DC. and Paspalum notatum Flüggé in subtropical grasslands of the Brazilian Pampa and Atlantic Forest. Pasture samples were randomly collected from eight sites selected to represent different climatic conditions of the southernmost grasslands of Brazil. Six sites were located in the Pampa biome [...] ABSTRACT Condensed tannins and α-tocopherol are important antioxidants produced by forage plants, with potential benefits for grassland sustainability and ruminant productivity. The objective of this study was to quantify the concentrations of phenolic compounds in Desmodium incanum DC. and Paspalum notatum Flüggé in subtropical grasslands of the Brazilian Pampa and Atlantic Forest. Pasture samples were randomly collected from eight sites selected to represent different climatic conditions of the southernmost grasslands of Brazil. Six sites were located in the Pampa biome

The objective of this work was to evaluate the performance and ingestive behavior of singleton and twin lambs after weaning under different feeding systems on tropical pasture. Studies were carried out over three years with castrated and weaned males of Texel x Corriedale lambs. In the first year, the treatments were: grass; grass and supplementation with concentrate (1.5% or 2.5% of live weight); grass and controlled legume grazing. In the second and third years, the treatments were: either grass or legume; mixed, this is, contiguous area of both grass and legume. On tropical pasture system, twin lambs fed with high levels of concentrate can gain more live weight than singletons, showing a compensatory growth and reaching the singletons live weight. Sheep litter size does not affect weaned lambs’ grazing behaviour under different feeding systems on tropical grassland. The use of concentrate supplementation changes lambs’ ingestive behavior by reducing grazing time and increasing idling time. Pigeon pea, as a monoculture or associated with grass, can be an important source of nutrients for lambs; however, it is not sufficient to ensure the same performance of twin and singleton lambs.

Large areas of tropical grass pastures are not grazed by lambs because of the difficulties in managing high growth rate swards with high selective animals. The objective of this study was to evaluate the physical and biochemical characteristics of tropical pastures offered to lambs in continuous grazing. An upright grass and a shrub legume were set out in three pasture types and grazed by lambs: (1) aruana grass monoculture (AG—Panicum maximum Jacq. cv. IZ‐5), (2) pigeon pea monoculture (PP—Cajanus cajan [L.] Millsp. cv. Anão) and (3) contiguous swards (CS), half of the paddock with AG (CSAG) and half with PP (CSPP). The pastures were evaluated for structural characteristics, production, nutritional composition and antioxidant concentrations in four periods over 92 days of continuous grazing by lambs. Hand plucking samples, similar to animal diet, were collected for chemical analysis. Regarding height, the PP legume monoculture after 42 days of grazing had uncontrollable growth by the lambs, reaching 1.2 m in height. This same legume but as a CS beside AG (CSPP) was maintained at a lower and similar height throughout the experimental periods. In general, the leaf:stem ratio of the different pastures decreased over the experimental periods from 0.7 to 0.2. In most periods, the CS showed intermediary nutritional quality compared to AG and PP. The alpha‐tocopherol content was similar among swards, with an average of 137.2 ± 13.67 mg/kg of green matter (p > .05). Pigeon pea showed the highest levels of total tannin and condensed tannin at 63 and 92 days (p < .05). The use of tropical grass together with a legume provides a better physical structure of the pigeon pea for grazing lambs than when monoculture of this species.

Our study investigated how different levels of antioxidants and contrasting proportions of native legumes in the diet affect lamb meat quality. Twenty-four male Texel lambs were randomly assigned to three groups: two groups on a natural pasture in southern Brazil (Pampa Biome), each at a different proportion of legumes: Low-legume (LL, 4.37%) and High-legume (HL, 14.01%); the other group was stall-fed (Control) to achieve the same growth rates as the grazing groups. Cold carcass yield from the Control lambs was higher than HL. The meat from pasture-fed animals had a higher deposition of muscle α-tocopherol and lower lipid oxidation (TBARS values) after 9 days of storage. LL lambs had higher subcutaneous fat thickness, which promoted better sensory quality of the meat, as assessed by a trained panel. Pasture-based diets enhanced odd- and branched-chain fatty acids (OBCFAs), trans vaccenic acid, and total conjugated linoleic acids (CLAs), while decreasing elaidic acid. Despite the lower ∆9-desaturase activity, the higher proportion of Desmodium incanum (condensed tannin-rich native legume) in the HL diet did not impact meat nutritional quality. Finishing lambs on the Pampa Biome grasslands is an option for improving the oxidative stability and beneficial fatty acid content of lamb meat, which improves product quality and human consumer health.

Tropical sward characteristics can alter lamb ingestive behavior. Our study evaluated the ingestive behavior of young lambs in different tropical pastures to identify which variables interfere in their grazing activity. Two years of study were carried out with 54 weaned lambs distributed in three different swards: 1) monoculture of a upright grass, guinea grass ( Panicum maximum ; GG); 2) monoculture of a shrubby legume pigeon pea ( Cajanus cajan ; PP) and 3) contiguous areas with half the paddock with GG and half with PP (GP). The experiment was set out in a randomized complete block design. Lamb ingestive behavior was observed from sunrise to sunset with records every 5 minutes. To identify the main variables that affected with the lamb grazing activity, a multivariate analysis of the Decision Tree was performed. Our results showed that there was no difference in the ingestive behavior parameters of young lambs in different swards ( P > 0.05). There was interaction among the swards and the experimental periods for the variables idleness time and biting rate ( P ≤ 0.05). Grazing time of the animals increased 40% with experimental period progression. The Decision Tree identified leaf:stem ratio as the variable that most influenced lamb grazing time in GG and GP swards while in the PP sward grazing time was directly related to the pasture height. The behavior of young lambs on tropical pasture is variable as there is a change in the behavioral response over time. In addition, the grazing time of these animals can be estimated by means of variables related to pasture structural characteristics (leaf:stem ratio and height) together with chemical variables.

The efficiency of grazing ruminant production systems is directly associated to the animals' ingestive behavior, and to structural characteristics of the pastures. The objective of this study was to evaluate the ingestive behavior of young lambs grazing three different heights of Capim Aruana (Panicum maximum). The experiment was carried out in two consecutive years, in which 30 tester lambs (4–5 months old) were equally divided into three paddocks (treatments) corresponding to different average sward heights of Aruana grass: (1) Tall-75 cm; (2) Medium-50 cm; and (3) Short-25 cm in a randomized block design. Ingestive behavior assessments were carried out every 28 days through 10-min observations of the main activities of the animals (grazing, ruminating, idling) and biting rate, from sunrise to sunset. In addition, the productive and qualitative characteristics of the pastures were assessed. Despite differences in pasture structure, grazing time (GT) and idling time were similar among treatments (P = 0.4266 and P = 0.2939, respectively). The shortest ruminating time (RT, P = 0.0181) was recorded in the treatment of lowest sward height. Lambs grazing on this treatment also showed 23% more bites per minute (P= < 0.0001) than animals in the Tall and Medium treatments. A Decision Tree analysis was performed for GT, identifying in a hierarchical order that the initial weight of the animals and sward height explained 62% (R² = 0.621) of the variation, representing the variables with the greatest influence on GT. Initial body weight explained 48% of the model. Thus, our research shows that the different sward heights of Capim Aruana mainly alter the lamb's RT and biting rate, and that the animals' initial body weight is a key factor influencing GT, given that this variable makes lambs more susceptible to changes in sward height.