Effect of condensed tannins in rations of lactating dairy cows on production variables and nitrogen use efficiency

Abstract

The objective of this study was to evaluate the effect of supplemented condensed tannins (CT) from the bark of the Black Wattle tree (Acacia mearnsii) on production variables and N use efficiency in high yielding dairy cows. A feeding trial with 96 lactating German Holstein cows was conducted for a total of 169 days, divided into four periods. The animals were allotted to two groups (control (CON) and experimental (EXP) group) according to milk yield in previous lactation, days in milk (98), number of lactations and BW. The trial started and finished with a period (period 1 and 4) where both groups received the same ration (total-mixed ration based on grass and maize silage, ensiled sugar beet pulp, lucerne hay, mineral premix and concentrate, calculated for 37 kg energy-corrected milk). In between, the ration of EXP cows was supplemented with 1% (CT1, period 2) and 3% of dry matter (DM) (CT3, period 3) of a commercial A. mearnsii extract (containing 0.203 g CT/g DM) which was mixed into the concentrate. In period 3, samples of urine and faeces were collected from 10 cows of each group and analyzed to estimate N excretion. Except for a tendency for a reduced milk urea concentration with CT1, there was no difference between groups in period 2 (CON v. CT1; P>0.05). The CT3 significantly reduced (P<0.05) milk protein yield, the apparent N efficiency (kg milk N/k feed N) and milk urea concentration; but total milk yield and energy-corrected milk yield were not affected by treatment. Furthermore, as estimated from 10 cows per group and using urinary K as a marker to estimate the daily amount of urine voided, CT3 caused a minor shift of N compounds from urine to faeces, as urea-N in urine was reduced, whereas the N concentration in faeces increased. As an improvement in productivity was not achieved and N use efficiency was decreased by adding the CT product it can be concluded that under current circumstances the use in high yielding dairy cows is not advantageous.

Effect of tannins and monensin on feeding behaviour, feed intake, digestive parameters and microbial efficiency of nellore cows

“…In the studies of Mokhtarpour et al (2017), Aguerre et al (2016), Ahnert et al (2015), Gerlach et al (2018b) and Perna Junior (2018) the different levels of tannins linearly reduced the urinary N and linearly increased the faecal N. This effect was also observed in this study (Table 7), but there was a reduction of N retention. The change in N excretion from urine to faeces is a widely known tannin effect (Theodoridou et al 2010).…”

“…The difference may be due to the level of tannins, since these authors included tannins up to 6%. The lack of effect of tannins on micN or EMNS was also observed by Aguerre et al (2016) and Mokhtarpour et al (2017), although they found a reduction on the concentration of rumen ammonia, but Gerlach et al (2018b) found reduction of EMNS. Oliveira et al (2007), using monensin, observed reduction of faecal N. This effect was also observed in the present study, and along with the increased protein digestibility, it may be thought that monensin was important on feed N utilisation.…”

“…This effect was not observed with tannins, where the CP digestibility linearly decreased, and as a consequence, the faecal N linearly increased. An increase in faecal N was also observed by Gerlach et al (2018b), who included tannins in Holstein diets. Ahnert et al (2015) also observed a linear increase of faecal N in diets with up to 6% of tannins.…”

Quantification of Methane and Ammonia Emissions in a Naturally Ventilated Barn by Using Defined Criteria to Calculate Emission Rates

“…A feeding trial consisting of four experimental periods was conducted with high-yielding dairy cows. By supplementing a commercial product rich in condensed tannins (CT), an attempt was made to decrease methane emissions and improve the animals’ nitrogen use efficiency, as previously described by [ 34 ]. A total of 96 lactating German Holstein cows (25% primiparous, 112 days in milk (DIM)) were randomly allocated to one of two groups (control (CON) and experimental group (EXP)) and balanced for means of lactation number, DIM, milk yield, and BW.…”

Tannin Supplementation in Animal Feeding; Mitigation Strategies to Overcome the Toxic Effects of Tannins on Animal Health: A Review

“…In dairy cows, CT increased milk quantity but no effects were observed on feed intake. However, various studies described that black wattle tree (Acacia mearnsii) bark containing CT concentration had no effects on dairy cows milk production (Gerlach et al, 2018). Dairy ewes fed quebracho tannins (QT) and acacia species had decreased milk yield.…”