Effect of tannin-containing hays on enteric methane emissions and nitrogen partitioning in beef cattle1

Abstract

The objective of this study was to determine whether feeding tannin-containing hays to heifers and mature beef cows influences enteric methane (CH4) emissions and nitrogen (N) excretion relative to feeding traditional legume and grass hays. Fifteen mature beef cows (Exp. 1) and 9 yearling heifers (Exp. 2) were each randomly assigned to treatment groups in an incomplete bock design with 2 periods and 6 types of hays with 3 hays fed each period (n = 5 cows and 3 heifers per treatment). Groups were fed tannin-containing [birdsfoot trefoil (BFT), sainfoin (SAN), small burnet (SML)] or non-tannin-containing [alfalfa (ALF), cicer milkvetch (CMV), meadow bromegrass (MB)] hays. Each period consisted of 14 d of adjustment followed by 5 d of sample collection. Nine cows and 9 heifers were selected for the measurement of enteric CH4 emissions (sulfur hexafluoride tracer gas technique), and excretion of feces and urine, while dry matter intake (DMI) was measured for all animals. The concentration of condensed tannins in SAN and BFT was 2.5 ± 0.50% and 0.6 ± 0.09% of dry matter (DM), respectively, while SML contained hydrolyzable tannins (4.5 ± 0.55% of DM). Cows and heifers fed tannin-containing hays excreted less urinary urea N (g/d; P < 0.001) and showed lower concentrations of blood urea N (mg/dL; P < 0.001) than animals fed ALF or CMV, indicating that tannins led to a shift in route of N excretion from urine to feces. Additionally, cows fed either BFT or CMV showed the greatest percentage of retained N (P < 0.001). Enteric CH4 yield (g/kg of DMI) from heifers (P = 0.089) was greatest for MB, while daily CH4 production (g/d) from heifers (P = 0.054) was least for SML. However, digestibility of crude protein was reduced for cows (P < 0.001) and heifers (P < 0.001) consuming SML. The results suggest that tannin-containing hays have the potential to reduce urinary urea N excretion, increase N retention, and reduce enteric CH4 emissions from beef cattle. The non-bloating tannin-free legume CMV may also reduce environmental impacts relative to ALF and MB hays by reducing N excretion in urine and increasing N retention.

Pasture chemoscapes and their ecological services

“…This effect was also observed when cattle were fed condensed tannin extracts in rations ( Koenig et al, 2018 ), as the high affinity of condensed tannins for binding protein reduces ruminal protein degradation and urinary N excretion. The same pattern of reduced urinary N excretion was observed in cows and heifers consuming tannin-containing hays (SF and BFT; Stewart, 2018 ), suggesting that condensed tannins remained active in the hay to bind with proteins in the rumen. Previous studies reported that condensed tannins are labile molecules, inactivated in response to the environmental conditions of the haying process ( Makkar and Singh, 1991 ).…”

In vitro digestibility of mountain‐grown irrigated perennial legume, grass and forb forages is influenced by elevated non‐fibrous carbohydrates and plant secondary compounds

“…More OM remained undigested in NDF isolates from tanniferous species that retained tannins in the NDF fraction. The HT in SMB bound more dietary N than the CT in BFT or SNF when beef cows were fed tannin‐containing hays as their complete diet 16 . Here, the NDF of SMB, with half the whole‐plant concentration of HT, had the greatest undigested OM.…”

“…The objective of this study was to compare the rate and extent of digestion of two non‐tannin (ALF and CMV) and two CT‐containing (BFT and SNF) legumes with a grass, meadow brome (MBG), and a non‐legume forb, small burnet (SMB), when these forages were grown under irrigation in the Mountain West region. Grasses have more fiber and less lignin than legumes, 5 and the non‐legume forb SMB is persistent and palatable to livestock but contains a hydrolysable tannin (HT) that reduces nitrogen excretion in the urine of beef cattle 16 . The in vitro gas production technique was used to study the influence of NDF, NFC, crude protein (CP), lignin, CT, HT, and other nutrients and secondary plant compounds on the rumen digestibility of these forages.…”

Ruminal Fermentation, Growth Rate and Methane Production in Sheep Fed Diets Including White Clover, Soybean Meal or Porphyra sp.

“…Brominated fatty acids are primarily synthesized by Asparagopsis [36]. Condensed tannins are suggested to reduce CH 4 production, as demonstrated in a Canadian experiment with beef cattle [37]. In Table 2, the content of condensed tannins is reported, and it shows small differences between the diets.…”