Megalac – comparison to other fat products
i) Megalac vs ‘50%’ fat supplement
A study undertaken at Scotland’s Rural College (SRUC) (UK) compared the effect of supplementing dairy diets with either Megalac or a ‘50%’ fat product at equal energy density. Eighteen early-mid lactation Holstein-Friesian dairy cows were split into three treatment groups in a Latin Square (change-over-type) design study with 28-d periods.
Two commercial fat supplements were included as treatments within this wider study and these data were analysed separately:
- Megalac rumen-protected fat - offered at 400 g/cow/d
- A ‘50%’ fat product - offered at 530 g/cow/d (equivalent to the energy supplied from 400 g of Megalac based on manufacturer’s data)
Specifications of the Megalac and ‘50%’ fat products as offered in the study are presented in Table 1.
Table 1 Specifications of Megalac and '50%' fat products
|Fat supplement offered|
|Crude protein %||0||1.7|
|Crude fibre %||0||24.5|
|ME (MJ/kg DM)*||33.3||27.0|
|Fatty acid profile (% of total fatty acids)|
Results from the study are presented in Table 2. Cows offered diets containing Megalac consumed 0.9 kg additional DM and produced 1.6 kg more milk per day (+5% increase) compared to those offered diets containing the ‘50%’ product. While fat supplement had no significant effect on milk fat % or milk protein %, milk fat yield (kg/d) was over 8% higher when cows were offered the diets containing Megalac. Cows offered Megalac-containing diets had higher live weight during the study – average 8 kg – and maintained condition score relative to the cows offered the ‘50%’ supplement, indicating that additional milk produced by the Megalac-supplemented cows was not at the expense of body fat, but a reflection of the efficient use of the additional energy supplied.
Table 2 Differences in fat supplement offered
|Fat supplement offered||SED||Sig|
|DM intake (kg/d)||20.0||19.1||0.26||**|
|Milk yield (kg/d)||33.7||32.1||0.57||*|
|Milk fat (%)||3.88||3.81||0.040||NS|
|Milk fat (kg/d)||1.30||1.20||0.028||**|
|Milk protein (%)||3.01||3.06||0.025||NS|
|Milk protein (kg/d)||1.01||0.97||0.021||NS|
|Live weight (kg)||629||621||2.1||**|
NS - Not significant, *P<0.05, **P<0.05
Kirkland, R.M. and Flockhart, J., 2015. Production performance of lactating dairy cows offered two different commercial fat supplements. British Society of Animal Science, Annual Conference, p77.
ii) Megalac compared to hydrogenated triglycerides
In a US study (Weiss and Wyatt, 2004), high yielding dairy cows were offered a control diet, or the control diet supplemented with either Megalac (at 1.75% or 3.4% of DM) or hydrogenated triglycerides of palm (at 1.6 or 3.2% of DM) in a Latin square design with 28-d periods.
The lower level of 1.75% Megalac used in this study equates to approximately 400 g/day, similar to typical levels used on farms. As presented in Table 3, intakes were similar to control cows, but the cows fed Megalac produced an additional 3.5 kg/day milk yield and milk fat was increased by 0.13%. Cows offered the hydrogenated triglyceride product had higher DM intakes but produced numerically less milk than cows offered Megalac. At the ‘high’ level of fat supplement (equivalent to 750 g Megalac/d), Megalac cows continued to produce more milk (+5.6 kg/d) compared to control cows while those offered the triglyceride supplement produced only 1.3 kg additional milk/d.
Table 3 Production data for cows supplemented with Megalac or hydrogenated triglycerides of palm oil¹
|DMI, kg/d||23.1||23.2||21.9||23.7||24.0||0.7||2, 3, 4|
|Live weight, kg||633||636||622||632||631||21||NS|
|Liveweight change, kg/d||0.36||0.24||0.08||0.21||0.03||0.17||NS|
|Milk, kg/d||38.0||41.5||43.6||41.1||39.3||2.9||1, 2, 4|
|4% FCM, kg/d||38.7||43.2||45.0||40.9||43.5||3.2||1, 3*|
|Fat, %||4.18||4.31||4.18||3.98||4.67||0.25||3*, 4|
|Fat, kg/d||1.57||1.78||1.84||1.63||1.85||0.15||1, 3*|
|Protein, %||3.07||3.00||2.82||2.99||3.03||0.13||1, 2, 3*, 4|
¹ Diets contained no supplemental fat or 1.7% (low) or 3.4% (high) from Megalac or hydrogenated triacylglycerides from palm oil (HPO)
² Contrasts (P<0.05, except *P <0.10): 1= control vs fat, 2 = source (Ca-PFA vs HPO), 3 = rate (low vs high) and 4= source x rate interaction. NS = P>0.10
Weiss, W.P. and Wyatt, D.J. 2004. Digestible energy values of diets with different fat supplements when fed to lactating dairy cows. J. Dairy Sci. 87, 1446–1454.