Urine volume and nitrogen excretion are altered by feeding birdsfoot trefoil compared with alfalfa in lactating dairy cows1

Abstract

Legumes that contain condensed tannins may have lower ruminal protein degradation than alfalfa. The present study investigated the effects of feeding birdsfoot trefoil (Lotus corniculatus L.) hay on lactational performance and N utilization and excretion. Eight multiparous Holstein cows in mid-lactation (150 ± 22.3 d-in-milk) were randomly assigned to two treatments [alfalfa hay-based total mixed ration (AHT) or birdsfoot trefoil hay-based total mixed ration (BHT)] in a crossover design with two experimental periods. Each experimental period lasted 17 d (14 d of adaptation and 3 d of sampling and total collection). Hays comprised approximately 50% of DM in experimental diets. There were no treatment effects on dry matter intake (DMI; 21.4 vs. 20.7 kg/d), milk yield (29.4 vs. 28.1 kg/d), milk fat concentration (3.20 vs. 3.21%), and milk protein concentration (3.20 vs. 3.16%) for AHT and BHT, respectively. In addition, dietary treatments did not affect milk yield/DMI or energy-corrected milk yield/DMI. In contrast, apparent crude protein digestion decreased in cows fed BHT compared to those fed AHT (60.7 vs. 69.1%). Concentration of milk urea-N decreased by feeding BHT compared with AHT (11.9 vs. 13.3 mg/100 mL), whereas total N excretion did not differ between AHT and BHT diets. However, cows fed BHT excreted more N in feces (194 vs. 168 g/d), while urinary N excretion was lower compared with cows fed AHT. Shift of N to feces resulted in a decrease in urinary-N:fecal-N ratio in cows fed BHT relative to those fed AHT. Overall results in the current study suggest that feeding birdsfoot trefoil in dairy diets shifts routes of N from urine to feces compared with feeding alfalfa hay, with little effect on lactational performance. Reduction in urinary N and any impact on environment may be attributed to functional effect of condensed tannins in birdsfoot trefoil hay.

Effect of Feeding Improved Grass Hays and Eragrostis tef Straw Silage on Milk Yield, Nitrogen Utilization, and Methane Emission of Lactating Fogera Dairy Cows in Ethiopia

“…Urinary N is more volatile and harmful to the environment than fecal N because the urinary urea N is inorganic N; microbial ureases rapidly hydrolyze urinary urea N to ammonium, which is then converted to ammonia, leading to N loss from the farm to the environment [ 50 ]. In agreement with our results, previous studies also reported that dairy cows fed large quantities of high-quality fresh forage or hay shift their excretion of N from urine to feces and thus toward sustainable dairy production [ 51 , 52 ]. The urinary N to fecal N ratio decreased from NPH to the TTS, NGH, and BhH diets; this indicates that using treated teff straw silage and improved forages as a basal diet in the TMR reduces urinary N excretion and indirectly mitigates ammonia emission in dairy cows for smart farming that is environmentally-friendly.…”

“…Therefore, the improved forage- and treated teff straw-based TMR diets we used as basal diets for dairy cows increased protein utilization efficiency and decreased the amount of N excreted to the environment per kg of milk produced. This indicates that inclusion of improved forages in the TMR diets of dairy cows can improve N efficiency [ 52 ].…”

“…In agreement with our findings, Migliano et al [ 59 ] likewise reported a strong positive correlation between ruminal ammonia N and plasma urea N. The inclusion of improved forages in TMR diets might contribute to highly degradable protein sources that decreased ruminal ammonia N concentrations, but ruminal ammonia N likely remained adequate for microbial growth [ 60 ]. The ruminal pH that we obtained is normal for lactating dairy cows fed roughage-based diets [ 52 ], perhaps because the dietary NDF concentrations of all of the dietary treatments were sufficient to maintain the optimal ruminal pH for cows fed high-forage diets. This might be mainly due to a high forage-to-concentrate ratio (70:30) [ 61 ].…”

Climate Change Impact, Adaptation, and Mitigation in Temperate Grazing Systems: A Review

“…Reduction in urinary N can also be achived though feeding livestock pastures or TMR containing birdsfoot trefoil or chicory. The bioactive compounds in particular condensed tannins help shifting routes of N from urine to feces [119]. This is particularly important to reduce N leaching problems in pastures.…”

Milk Production, N Partitioning, and Methane Emissions in Dairy Cows Grazing Mixed or Spatially Separated Simple and Diverse Pastures

“…Decreased urinary N output and increased milk N output in cows grazed on diverse pastures with low CP suggest a shift in the utilization of N [ 7 ]. The presence of substantial amount of bioactive compounds, including diuretic molecules, is the main reason chicory and plantain reduce urea level and overall N output and partition the N toward milk in dairy cows [ 7 , 50 ]. Higher utilization of N accompanied by a decrease in urinary N output was observed in dairy cows when chicory was incorporated into pasture mixtures [ 7 , 51 ].…”