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OREGANO AS AN ADDITIVE TO ENHANCE RUMEN FERMENTATION.

Oregano, Origanum vulgare, is a natural anti-bacterial compound affecting a variety of gram positive and gram negative bacteria in the rumen. It may have potential to improve the overall health and production of a lactating dairy cow by enhancing rumen fermentation. The aim of the study cited below was therefore to determine the effect of   Oregano, which is an essential oil, on milk production and rumen fermentation of Jersey cows grazing ryegrass pasture during spring.

Fifty four early lactation Jersey cows of the Outeniqua herd were blocked according to days in milk, 4% fat corrected milk (FCM) and lactation number. The cows within these blocks were randomly allocated to one of three treatments: (1) A Control treatment, which was a maize based concentrate with no feed additives; (2) An ionophore treatment, which was the maize based concentrate with monensin at 300mg per cow per day; and (3) The essential oil treatment, which was the maize based concentrate with Oregano at 1.15g per cow per day. The concentrate (DM basis) consisted of 68.8% maize meal, 14.7% hominy chop, 6% molasses syrup, 70% soya bean oilcake, 1.5% feed lime, 0.5% mono-calcium phosphate, 0.6% salt, 0.3% magnesium oxide and 0.6% premix containing the two feed additives monensin and oregano. The cows were milked twice a day and received 3kg concentrate twice per day during milking. Pasture allowance was estimated at 10 kg DM per cow per day, divided into two grazing periods after each milking. The cows were allocated an adaptation period of 14 days and a measurement period of 67 days. Milk yield was recorded daily and composite milk samples were collected per cow twice per week. Milk samples were analysed for fat, protein, lactose, milk urea nitrogen and somatic cell content. Live weight (LW) and body condition score (BCS) were determined on two consecutive days at the start and the end of the study. Six rumen cannulated cows were used in the rumen study. Two cows were randomly allocated to each of the three treatments (Control, Monensin and Oregano) in a 3x3 Latin square design. Ruminal pH, volatile fatty acids (VFA) concentration and ruminal ammonia-nitrogen (NH3-N) were determined. The in sacco ruminal degradability of ryegrass pasture dry matter (DMd) and neutral detergent fibre (NDFd) were measured at incubation times of 6 and 30 hours in the rumen.

The daily average milk yield, 4% FCM and milk fat content did not differ between treatments  and were respectively 20.5, 20.3 and 20.4 kg per cow; 22, 21.5 and 22 kg per cow and 4.52, 4.47 and 4.56% for the cows on the Control, Monensin and Oregano treatments. The milk protein and lactose content increased for the two additive treatments in comparison to the Control and were respectively 3.39a, 3.55b and 3.6b% and 4.52a, 4.79b and 4.83b% for the cows on the  Control, Monensin and Oregano treatments. Cows in all three treatments showed an increase in LW and BCS, with no differences between treatments. The in sacco dry matter degradability at 6 hours incubation did not differ between treatments. The DMd and NDFd at 30 hours incubation were higher for the two additive treatments in comparison to the Control where the degradability was respectively 82.5a, 84.7b and 84.4b% DMd% and 74.8a, 78.1b, 78.1b% for NDFd% for the Control, Monensin and Oregano treatments. The results showed that supplementation with Oregano, as with monensin, resulted in an increase in milk protein and lactose, and an increase in pasture DM and NDF degradability. Oregano as supplement thus appears favourable to rumen fermentation and nutrient utilization for milk component synthesis and can therefore be included when available.

Reference:

Z. Moller, R. Meeske & C.W. Cruywagen, 2015. The use of Oregano as feed-additive for dairy cows grazing on ryegrass pasture in spring. Proc. of the 48th SASAS Congress, 21-23 September 2015, Empangeni.