Energy, protein and water gap analysis in dairy cows kept under cut and carry fodder based feeding system

Description

There is a gap in dry matter, water, energy and protein intake of dairy cows kept in fodder-based diets undercut and carry feeding systems in Sub-Saharan countries, Rwanda included. A study was conducted in two contrasting areas of Rwanda: Eastern Savana and Volcanic highlands. The objective was to determine dry matter, water, protein, and energy intake in comparison to their requirements for meeting the potential milk production of lactating dairy cows. Ninety households, including 66 from the lowlands and 30 from the highlands, were randomly selected, and a total of 96 cows were included in the data collection process. About 96 samples that corresponded to different fodder mixtures fed to lactating dairy cows in surveyed households were analyzed for their dry matter (DM), crude protein (CP), neutral detergent fibre (NDF), and metabolizable energy (ME). Data on NDF intake, ME and CP intake, water, DM intake, body weight, and milk performance were also collected. Data on feed characterization were computed with Farm DESIGN Manual models by Groot and Oomen, while data for the production requirement of dairy cows under lactation were computed using LIGAPS dairy models. Data were analyzed using a general linear model with univariate analysis of the statistical package for social sciences (SPSS). Results on feed characteristics showed that the average nutritive value of offered fodder was 25% DM, 58.5% NDF, 9.8% CP, and 6 megajoules (MJ) per kg DM of ME. Results on production management showed that the average daily intake was 9kg DM; 35 litres of water; 898g of crude protein (CP) and 55 MJ ME, resulting in milk production of 8.8 litres per day in both sites. However, the average requirement for both maintenance and a target milk production of 16.5litres per day were 15kg of DM; 57 Litres of water, 1907g of CP, and 137 MJ of ME. This indicated daily deficits of 6kg DM, 21.6litres of water, 1094g of crude protein, and 83.7 MJ of ME, along with a 7.6-litre shortfall in milk yield per day. The results of the present study demonstrate the hypothesis previously posed. Findings from this analysis will serve as instruments for researchers in developing dairy diet models to improve dairy cow productivity at the household level. Demonstrating the gap in available feed resources would trigger the uptake of new feeding technologies by farmers. For dairy feed manufacturers, this would serve as a guide for proper rationing of high-concentrate ingredients rich in energy and protein in consideration of their requirements. This would contribute to improved milk production resulting in better remuneration to farmers, increased national milk pool, and per capita milk consumption.

Steps to reproduce

Data were collected by cross sectional method by trained enumerators after a pre-testing session. Body weights of the lactating cows were taken using a tape meter before morning feeding. Daily milk production records was done with graduated plastic jars after each milking session. Water intake was recorded based on the number of graduated Jeri cans distributed to cows in the course of a day. Feed supplied were measured using a hanging balance and summed up to a total amount of fresh weight per day. Leftover feeds were weighed the next morning by the technician. Daily feed intake corresponded to the difference between served feeds and leftovers. To identify most available feeds resources used for feeding lactating dairy cows, samples of 250g of composites fodder were taken by the technician per household to characterize the nutritive value ingested by lactating dairy cows per day. Ninety nine (99) mixed fodder samples were analysed for dry matter (DM), crude protein (CP), neutral detergent fibre (NDF), and metabolizable energy (ME) in the analytical laboratory of Rubona station of Rwanda Agriculture and Animal Resource Development Board (RAB). The dry matter feed requirement for body maintenance of cows DMIR=BW x 3.5/100 (Equation 1). Free water intake requirement=12.3+2.15 x DMIR+0.73 x PM. (Equation 2). Where DMIR= dry matter intake requirement and PM= Potential milk The potential milk production of multiparous cows was set based on potential milk of each cow. ME in feeds (MJ/kg DM) was according to by Groot et al (2016). Hence ME in feeds (MJ/kg DM) = 2.2 + 0.136 G24 + 0.057CP + 0.0029CP2 (Equation 3). Required ME for both maintenance and milk production was estimated according to the LIGAPs-dairy model by Van der Linden et al. (2021) where 0.589 MJ per kg metabolic weight is required for maintenance, and 5.023 MJ is required per kg milk. Energy maintenance = BW^0.75 x 0.589 (Equation 4). Where BW^0.75= is the metabolic weight; Energy for potential milk=5.023 x potential milk; (Equation 5). Total energy for potential production=energy for maintenance + energy for potential milk. The gap in energy intake was the value obtained by subtracting ME intake from total energy for potential production. Protein intake was expressed as crude protein (CP) intake. Therefore, CP intake=CP in feeds x DMI where CP in feeds (gr/kg DM) = % CP x 1000/100 and DMI=dry matter intake. Required protein for both maintenance and production was estimated according to the LIGAPs-dairy model by Van der Linden et al. (2021). In the model, 6.27g CP per kg metabolic weight is required for maintenance and 82g CP is required per kg milk. Therefore, the CP requirement for maintenance = 6.27 x MW. (Equation 6). Where; MW= metabolically weight; CP requirement for potential milk= 82g x potential milk; (Equation 7). Total CP requirement for potential production=CP maintenance + CP potential milk. Gap CP= Total CP required for potential production - CP intake

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