NUTRITIONAL AND FEEDING STRATEGIES TO REDUCE METHANE EMISSION FROM DAIRY COWS
Creators: name: PIRONDINI, MARIO
Publisher: name: Universit� degli Studi di Milano
Year: 2014

description: The general aim of the present thesis was to evaluate the effects of several nutritional and feeding strategies to reduce methane (CH4) production from dairy cows. The thesis includes the results of three experiments conducted with the financial support from EU Research Project LIFE 09 ENV/IT/0214 Gas-Off. The aim of the first study was to measure total gas and CH4 production from 30 total mixed rations (TMRs) fed to dry and lactating cows in 20 commercial dairy farms of the Po Plain (Italy). Samples were analyzed for chemical composition, in situ 48 h fiber digestibility (NDFD) and in vitro gas production (GP) and CH4 concentration at 24 h of incubation. Neutral detergent fiber digestibility of TMRs from dry and lactating cows was identical (52.1%; P=0.995). The TMRs fed to dry and lactating cows differed for GP (43.0 and 54.4 mL/200 mg DM, respectively; P&lt;0.001) and CH4 (7.24 and 8.85 mL/200 mg DM, respectively; P=0.001), but not for CH4 as percentage of GP (24.3 and 23.7%, respectively; P=0.286). Data were also analyzed dividing the TMRs into quartiles depending on ?starch:ADF? ratio; the average ratios of the groups 1, 2, 3 and 4 were 37, 77, 116 and 138, respectively. Increasing ?starch:ADF? ratio determined a higher GP: 42.2, 51.4, 55.1 and 56.2 mL/200 mg DM for groups 1, 2, 3 and 4, respectively (P&lt;0.001), whilst CH4 (mL/200 mg DM) was lower (P&lt;0.001) for group 1 (7.12) in comparison with the others (8.82 on average). Acetate, expressed as percentage on total volatile fatty acids (VFA) decreased for increasing ?starch:ADF? ratio (P=0.009), whereas butyrate tended to increase (from 8.11 to 9.23% on total VFA; P=0.069) and the ?acetate:propionate? ratio to decrease (from 3.35 to 3.09; P=0.082). The lack of a higher CH4 concentration in GP from diets richer in fiber might be attributed mainly to the relatively short time of incubation. The second trial was aimed to evaluate at first the effects of 18 essential oils, yeast, Quebracho tannin and Quillaja saponin on ruminal methane and gas production (GP) in vitro. A lactating cow diet was incubated with rumen inoculum. Doses of the additives (mg/L) were: essential oils=500; tannin=67; yeast=8.35 and 16.7; saponin=300. Lemongrass, estragole, eugenol, geraniol, limonen, thyme oil and thymol produced less gas (overall mean 33.8 mL/200 mg DM) than control (43.6 mL/200 mg DM; P&lt;0.001). Methane produced (mL/200 mg DM) by guaiacol (10.7), lemongrass (9.6), limonene (11.4), thyme oil (10.9) and thymol (2.1) was lower than control (12.5) (P&lt;0.001). Methane percentage on total GP was lower (P&lt;0.001) for cinnamic alcohol (25.4), guaiacol (24.5), thymol (19.7) and vanillin (26.3) than control (28.8). In the second part of the experiment, thymol, guaiacol and yeast were added to the diet of dry fistulated cows to determine in situ NDF digestibility (NDFD) of six forages and in vivo dietary NDFD. Thymol and yeast decreased in situ NDFD after 24 h (33.9% and 33.5% vs 38.1%; P=0.008). Thymol decreased in vivo total tract NDFD (40.8% vs. 51.4%; P=0.02). Differences in GP and methane levels were registered within classes of additives. A careful selection of additives may allow for the manipulation of ruminal fermentation. The third experiment was conducted to evaluate the effects of diets with different starch contents and fish oil (FO) supplementation on lactation performance, in vivo total-tract nutrient digestibility, N balance and methane (CH4) production in lactating dairy cows. The experiment was conducted as a 4�4 Latin square design with a 2�2 factorial arrangement: two levels of dietary starch content (low vs high), the presence or absence of FO supplement (0.80% DM) and their interaction were evaluated. Four Italian Friesian cows were fed one of the following four diets in four consecutive 26-d periods: 1) low starch (LS), 2) low starch plus FO (LSO), 3) high starch (HS) and 4) high starch plus FO (HSO). The diets contained the same amount of forages (corn silage, alfalfa and meadow hay). The starch content was balanced using different proportions of corn meal and soybean hulls. The cows were housed in metabolic stalls inside open-circuit respiration chambers to allow the measurement of CH4 production and the collection of separate urine and feces samples. No differences among treatments were observed for dry matter intake: neither FO nor the use of soybean hulls negatively influenced this parameter (22.9 kg/d, on average). A trend was observed for the effect of FO on milk yield (P=0.10), with a higher milk production compared with the diets without FO (29.2 vs 27.5 kg/d on average, respectively). Moreover, FO supplementation favorably decreased the n-6:n-3 ratio of the milk polyunsaturated fatty acids (PUFA). Consistent with the literature, the milk protein percentage was negatively influenced by FO (P&lt;0.01): 3.37% on average for the LSO and HSO diets vs 3.67% for the LS and HS diets. With regard to digestibility, the HS diet negatively influenced all the parameters measured, with starch as the only exception. The percentage of N intake excreted with feces was influenced by both the FO (P=0.09) and starch content (P=0.04): the HS diet showed the highest value, followed by the HSO and LS diets and finally by the LSO diet. With regard to methanogenesis, there was a trend (P=0.08) of lower CH4 emissions (g/d) with the HS and HSO diets compared with the LS and LSO diets (396 vs 415 on average, respectively). Fish oil supplementation did not reduce methanogenesis. Previous in vitro studies have demonstrated a reduction in CH4 production as a consequence of FO supplementation; the decrease in CH4 production is generally accompanied by marked reductions in dry matter and fiber digestibility, which were not observed in the present work.