A Nutritional Investigation of Major Feed Types and Feed Rations Used in Medium-Scale Dairy Production Systems in Sri Lanka.

Abstract

Simple SummaryLittle information is available regarding the feeding of dairy cattle in Sri Lanka or the impact of feeding on productivity. The aim of this study was to catalogue the availability, quantity, and composition of feeds, to identify the feeding regimens used, and to calculate dietary metabolisable energy (ME) and crude protein (CP) in order to investigate shortfalls in dietary requirements. The ME and CP contents of the abundantly used forages (representing > 50% of the cow diet) Guinea ecotype A and Hybrid Napier CO-3 grasses were generally low (7.5–8.0 MJ/kg DM, 8.0–8.8% DM, respectively), and were lower than that of legumes (i.e., Gliricidia: 10.0 MJ/kg DM, 17.7% DM, respectively). Daily ME intake was consistently 10% lower than the calculated daily energy requirements as a consequence of the low nutritive values of these forages and of farmers’ consistent overestimation of their quality. The CP intake of lactating cows (13.5% DM) was inadequate to meet their requirements (16–18.5% DM), whereas the CP intake of dry cows (11.8% DM) adequately met requirements (11–12% DM). Based on the results of this study, limitations on nutritional requirements adversely affect milk production of dairy cows in Sri Lanka.In this paper, the nutritional quality, digestibility, and chemical composition of major feed types as well as the use of those feeds in rations by medium-scale dairy farmers in the Kurunegala district of Sri Lanka were studied. Nine dairy farms were visited fortnightly over a five-month period to identify the feeds that were commonly used. All farms operated under a stall-feeding system in which a manually mixed ration (MMR) was fed 2–3 times daily. Four forages were identified: Guinea grass ecotype A (Panicum maximum), called Guinea grass; Hybrid Napier CO-3 (Pennisetum purpureum × Pennisetum americanum), called CO-3 grass; Gliricidia (Gliricidia sepium); and maize stover (Zea mays L.), along with three other supplementary feeds (maize silage, barley distillers’ by-products, and commercially formulated cattle feed). These feeds were subjected to proximate analysis and in vitro digestibility analysis. The metabolisable energy (ME) of the forages ranged from 7.5–10.0 MJ/kg dry matter (DM), with the ME of Guinea grass and CO-3 grass (7.5 and 8.0 MJ/kg DM, respectively) being lower than that of Gliricidia (10.0 MJ/kg DM). The neutral detergent fibre (NDF) concentration of both Guinea grass and CO-3 grass (both 72% DM) was much higher than that of Gliricidia (47% DM). Crude protein (CP) was higher in Gliricidia (17.5% DM) than in either Guinea grass or CO-3 grass (8.0 and 8.8% DM, respectively). The ME of the supplementary feeds varied between 11.0 and 12.8 MJ/kg DM, while CP varied between 15.0 and 24.0% DM. The daily ME intake of cows was consistently 10% lower than their calculated daily energy requirement; for dry cows, the mean intake was 90 MJ/cow/day supplied vs. 101 MJ required, while for cows in early lactation the mean intake was 126 MJ/cow/day supplied vs. 140 MJ required. The average CP intake of lactating cows (13.5% DM) was inadequate (requirements: 16 to 17.5% DM), while the average CP intake of dry cows (11.8% DM) was satisfactory (requirements: 11 to 12% DM). The current study shows that the majority of the feed types used in these medium-scale dairy farms provide insufficient ME or CP to meet the nutritional requirements of either lactating or dry cows irrespective of the quantity of feed provided.