Table 1 – Effect on milk production and feed efficiency (Source: Schothorst Feed Research) Dry matter intake (kg/day)
Fat-corrected milk yield (FCM, kg/day) Butterfat production (kg/day)
Feed efficiency (kg FCM/ kg DMI) 1 Vistacell at 4g/cow/day
Control 23.4 37.1 1.46 1.59
2 Vistacell AB = Vistacell at 4g/cow/d + Acid Buf at 88g/cow/day
AB) containing both the yeast and a calcareous marine algae-based slow-release rumen conditioner (Acid Buf at 88g/cow/day). “The results are shown in Table 1, with the increase in milk fat
production equating to a rise from 3.89% butterfat in the control to 4.18% where yeast was used alone and 4.53% for the combination of yeast and conditioner,” explains Dr McIlmoyle. “What’s particularly interesting is that using both together didn’t increase DMI, but did increase milk yield and butterfat production. “That increase in overall feed conversion efficiency is confirmed
by the 3% rise in production per unit of DMI, from 1.60 kg FCM/kg DMI for the yeast alone to 1.65 kg FCM/kg DMI where the rumen conditioner was also added. It’s a direct consequence of improved rumen fermentation.” Figure 1 shows the clear reduction in time that rumen contents
spent below certain pHs following addition of the yeast and conditioner, with pH 5.8 being the critical point below which fibre digestion is compromised. Below pH 5.5 is the point at which cows are considered to be suffering from SARA.
Figure 1 – Effect on rumen pH (Source: Schothorst Feed Research)
Table 2 – Effect on VFA concentration (Source: Schothorst Feed Research)
Control
Acetate (mol/100 mol VFA) Propionate (mol/100 mol VFA) Butyrate (mol/100 mol VFA) Acetate : Propionate ratio
61.9 22.2 13.0 2.8
Yeast only
61.4 22.8 12.8 2.7
Yeast plus conditioner
63.1 20.2 13.6 3.1
The consequent reduction in propionate concentration meant there
was also a significant increase in the acetate to propionate ratio, which is a key indicator of how well the rumen is fermenting fibre. “For milk producers looking to boost butterfats, maximise milk
Increased margin potential “The impact this has on fibre digestion is highlighted by the differences in VFA concentration between the treatments,” adds Dr McIlmoyle. “Levels of acetate and butyrate – both key precursors for milk fat synthesis – were significantly higher where the combination of yeast and conditioner was used, compared to either the control or the use of yeast alone (see Table 2).”
value and improve overall feed efficiency, this research has important implications,” Dr McIlmoyle concludes. “What’s clear is that it’s no longer a simple question of whether a yeast or a rumen conditioner will be the best option to help maintain good rumen conditions and milk fat production. “It appears that there’s a benefit to using both at the same time,
with the potential performance advantage more than sufficient to justify the additional cost.”
FEED COMPOUNDER JANUARY/FEBRUARY 2019 PAGE 29
Yeast only1 24.2 38.6 1.58 1.60
Yeast plus conditioner2 23.6 38.9 1.65 1.65
One of the growing challenges facing milk producers is that modern Holstein Friesians are genetically programmed to produce large volumes of milk regardless of whether adequate rations are provided. Any failure to provide a properly formulated diet will both reduce milk output and force the cow to draw on valuable body reserves in an effort to maintain production.
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