Methane production, nutrient digestion, ruminal fermentation, N balance, and milk production of cows fed timothy silage- or alfalfa silage-based diets

Abstract

The objective of this study was to investigate the effects of changing forage source in dairy cow diets from timothy silage (TS) to alfalfa silage (AS) on enteric CH 4 emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3 × 3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio of 60:40, dry matter basis), with the forage portion consisting of either TS (0% AS; 0% AS and 54.4% TS in the TMR), a 50:50 mixture of both silages (50% AS; 27.2% AS and 27.2% TS in the TMR), or AS (100% AS; 54.4% AS and 0% TS in the TMR). Compared with TS, AS contained less (36.9 vs. 52.1%) neutral detergent fiber but more (20.5 vs. 13.6%) crude protein (CP). In sacco 24-h ruminal degradability of organic matter (OM) was higher for AS than for TS (73.5 vs. 66.9%). Replacement of TS with AS in the diet entailed increasing proportions of corn grain and bypass protein supplement at the expense of soybean meal. As the dietary proportion of AS increased, CP and starch concentrations increased, whereas fiber content declined in the TMR. Dry matter intake increased linearly with increasing AS proportions in the diet. Apparent total-tract digestibility of OM and gross energy remained unaffected, whereas CP digestibility increased linearly and that of fiber decreased linearly with increasing inclusion of AS in the diet. The acetateto-propionate ratio was not affected, whereas ruminal concentration of ammonia (NH 3 ) and molar proportion of branched-chain VFA increased as the proportion of AS in the diet increased. Daily CH 4 emissions tended to increase (476, 483, and 491 g/d for cows fed 0% AS, 50% AS, and 100% AS, respectively) linearly as cows were fed increasing proportions of AS. Methane production adjusted for dry matter intake (average = 19.8 g/kg) or gross energy intake (average = 5.83%) was not affected by increasing AS inclusion in the diet. When expressed on a fat-corrected milk or energy-corrected milk yield basis, CH 4 production increased linearly with increasing AS dietary proportion. Urinary N excretion (g/d) increased linearly when cows were fed increasing amounts of AS in the diet, suggesting a potential for higher nitrous oxide (N 2 O) and NH 3 emissions. Efficiency of dietary N use for milk protein secretion (g of milk N/g of N intake) declined with the inclusion of AS in the diet. Despite marked differences in chemical composition and ruminal degradability, under the conditions of this study, replacing TS with AS in dairy cow diets was not effective in reducing CH 4 energy losses.

Volatile Fatty Acids in Ruminal Fluid Can Be Used to Predict Methane Yield of Dairy Cows

“…The components of MSEP were 0.62 for error-of-central-tendency, 0.20 for error-due-to-regression, and 8.1 for error-of-disturbance. Similar results were obtained for Equations (3) and 7 4, and (c) Equation 7showing the observed methane yield against equation-predicted methane yield, for 32 individual [6], (open circles) and 67 treatment means from 16 previously published experiments [14,[36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51] (closed circles) with 1:1 line of agreement (dashed).…”

Biogenic amines and hygienic quality of lucerne silage

“…Similar findings were reported by Filya et al [28] and Holzer et al [24]. Hassanat et al [29] report from their experimental work values of ADF, NDF, lactic acid and acetic acid similar to those determined in our experimental lucerne silages, as well as similar absence of propionic acid and butyric acid.…”

Associative effects of ensiling mixtures of sweet sorghum and alfalfa on nutritive value, fermentation and methane characteristics

“…Hassanat et al (2014) found the ruminal concentration of branched-chain VFA increased as cows were fed higher proportions of AF silage in the diet. Also, in agreement with our results, other researchers (Haddad, 2000;Saro et al, 2014) have reported that the rumen total VFA were increased as proportions of AF were increased in diets.…”