Exploring improved tropical forages is considered to be an important approach in delivering quality and consistent feed options for dairy cattle in tropical and subtropical regions. The present study aimed to study the suitability of three improved tropical grasses, Chloris gayana ‘Rhodes grass cv. Reclaimer’ (RR), Megathyrsus maximus ‘Gatton Panic’ (GP), and Brachiaria ruziziensis x B. decumbens x B. brizantha ‘Brachiaria Mulato II’ (BM) evaluating their carbon assimilation, canopy structure, herbage plant–part accumulation and quality parameters under irrigated conditions. An experiment was conducted at Gatton Research Dairy (27°54′ S, 152°33′ E, 89 m asl) Queensland, Australia, which has a predominantly subtropical climate. Photosynthesis biochemistry, canopy structure, herbage accumulation, plant part composition, and nutritive value were evaluated. Photosynthesis biochemistry differed between pasture species. Efficiency of CO2 assimilation was highest for GP and quantum efficiency was highest for BM. Pasture canopy structure was significantly affected by an interaction between pasture species and harvest. Forage biomass accumulation was highest in GP, while BM produced more leaf and less stem compared to both GP and RR. A greater leafy stratum and lower stemmy stratum depth were observed in the vertical sward structure of BM. Brachiaria Mulato II showed greater carbon partitioning to leaves, leaf: stem ratio, canopy, and leaf bulk density. It also demonstrated greater nutritive value (Total digestible nutrients (TDN), acid detergent fibre (ADF), neutral detergent fibre (NDF), neutral detergent insoluble protein (NDICP), Starch, nonfibre carbohydrates (NFC), metabolisable energy (ME), mineral profile (Mg, P, K, Fe, Zn) and dietary cation–anion difference (DCAD) for leaf, stem, and the whole plant. Greater quantum efficiency, leaf accumulation, and nutritive value of BM observed in the present study suggest BM as an attractive forage option for dairying that warrants further research in pasture-based systems in tropical and subtropical climates.

The demand for dairy products is ever increasing across the world. The livestock sector is a significant source of greenhouse gas (GHG) emissions globally. The availability of high-quality pasture is a key requirement to increase the productivity of dairy cows as well as manage enteric methane emissions. Warm-season perennial grasses are the dominant forages in tropical and subtropical regions, and thus exploring their nutritive characteristics is imperative in the effort to improve dairy productivity. Therefore, we have collated a database containing a total of 4750 records, with 1277 measurements of nutritive values representing 56 tropical pasture species and hybrid cultivars grown in 26 different locations in 16 countries; this was done in order to compare the nutritive values and GHG production across different forage species, climatic zones, and defoliation management regimes. Average edaphoclimatic (with minimum and maximum values) conditions for tropical pasture species growing environments were characterized as 22.5 °C temperature (range 17.5–29.30 °C), 1253.9 mm rainfall (range 104.5–3390.0 mm), 582.6 m elevation (range 15–2393 m), and a soil pH of 5.6 (range 4.6–7.0). The data revealed spatial variability in nutritive metrics across bioclimatic zones and between and within species. The ranges of these nutrients were as follows: neutral detergent fibre (NDF) 50.9–79.8%, acid detergent fibre (ADF) 24.7–57.4%, crude protein (CP) 2.1–21.1%, dry matter (DM) digestibility 30.2–70.1%, metabolisable energy (ME)3.4–9.7 MJ kg−1 DM, with methane (CH4) production at 132.9–133.3 g animal−1 day−1. The arid/dry zone recorded the highest DM yield, with decreased CP and high fibre components and minerals. Furthermore, the data revealed that climate, defoliation frequency and intensity, in addition to their interactions, have a significant effect on tropical pasture nutritive values and CH4 production. Overall, hybrid and newer tropical cultivars performed well across different climates, with small variations in herbage quality. The current study revealed important factors that affect pasture nutritive values and CH4 emissions, with the potential for improving tropical forage through the selection and management of pasture species.

Dairy farming remains the economic backbone of livestock farmers in high potential area like Badulla district in Sri Lanka. Though, milk production has been quite low. Therefore, this study was carried out to investigate the factors affecting dairy cattle milk production in Badulla. Total of 500 dairy farmers were selected using multistage stratified and simple random sampling techniques. Milk production and socioeconomic data were collected using a pre-tested structured questionnaire covering 15 divisional secretariats in Badulla. Data were analyzed for descriptive and inferential statistics followed by regression analysis. Results of the study revealed that the intensive dairy cattle farming is operated (87.14%) in up country wet zone. Jersey breed was the major breed (86.4%) accounting for 6.19 L/cow average daily milk production. The highest (10.89±1.73 L/cow/day) and lowest (3.17±0.38 L/cow/day) milk productions were reported in Haputhale and Mahiyangana, respectively. The best fitted multiple linear regression model predicted that R2 value of 62.91% daily milk production suggesting farmers experience, farmer's age, number of milking cows, forage type, shed condition, concentrate feeding supplement, frequency of concentrate supplement, frequency of water supplement, calves feeding amount age at wean, feeding method of cow, mineral supplement and monthly income of the farmers were significantly (p<0.05) affected by the daily milk production of Badulla district. However, lack of high yielding cross breeds, less success rate in artificial inseminations, low quality pasture and seasonality in pasture production, poor milk collection network and low farmer gate price, high price of concentrates, and inadequate facilities for animals in the estate area were reported as key constraints which need to be properly focused on in future to increase milk production in Badulla district, Sri Lanka.