PALM KERNEL EXPELLER AS AN INGREDIENT IN CONCENTRATE SUPPLEMENTATION ON PASTURES

The nutrient requirements of high-producing dairy cows obviously cannot be satisfied by high quality pasture only.  Supplements can overcome the shortage, but at the cost of potentially substituting pasture dry matter intake (DMI). Supplements are also cost sensitive and are affected by the continuous fluctuation in feed prices. Consequently, improving the efficiency of production and reducing the cost of concentrate supplements are becoming increasingly important. High maize and oilcake prices have a substantial impact on the production cost of milk. Maize grain can constitute 70 to 80% of a conventional dairy concentrate and soybean oilcake 8 to 12%. Concentrates may contribute up to 65% of the total feed cost in pasture dairy grazing systems and, therefore, efforts should always be made to replace expensive energy and protein sources by less expensive by-product feeds; palm kernel expeller being an example.

The aim of the study of van Wyngaard and co-workers at Outeniqua was to determine the effect of different inclusion levels of palm kernel expeller (PKE) in dairy concentrates for grazing Jersey cows on lactation performance and rumen fermentation patterns. Forty-eight multiparous Jersey cows, grazing kikuyu-ryegrass during spring, were blocked according to 4% fat-corrected milk, days in milk and lactation number and randomly allocated to three treatments based on PKE level in the concentrate. The PKE inclusion in the control (C), low PKE (LP), and high PKE (HP) treatment concentrates was 0, 20 and 40%, respectively. These were fed for 60 days, preceded by a 21 day adaptation period. The PKE partially substituted some of the maize and soybean in the concentrate. Additionally, eight rumen-fistulated, lactating dairy cows were randomly allocated to the C and HP treatments in a two period cross-over design. All cows received 6 kg (as is) concentrate per day divided over two milkings and they strip-grazed pasture as one group.

Milk yield and milk fat content did not differ between treatments and were 21.3, 21.3 and 20.7 kg per cow per day and 4.63, 4.65 and 4.66% for the C, LP and HP treatments, respectively. Milk protein, milk urea nitrogen, body weight and body condition score did not differ either. Total volatile fatty acid, mean ruminal pH, ammonia nitrogen, and in situ pasture dry matter and neutral detergent fibre degradability (simulates rumen fermentation rate) also did not differ between treatments. The acetic to propionic acid ratio was significantly higher for cows receiving treatment HP compared to cows receiving treatment C (3.40 vs 3.22), which reflects the slightly higher fibre content on the high PKE diet. It was concluded that PKE can sustain milk yield and milk fat components at a level of up to 40% of the concentrate when the supplement is fed at 6 kg per cow per day to cows grazing a kikuyu-ryegrass pasture. The authors, however, recommended that a more practical approach would be to limit PKE to 20% of the concentrate supplement as palatability problems were noticed, resulting in a slow rate of intake when fed during milking in the parlour.

Reference:

J.D.V. van Wyngaard, R. Meeske & L.J. Erasmus. 2015. Effect of palm kernel expeller as supplementation on production performance of Jersey cows grazing kikuyu-ryegrass pasture. Anim. Feed Sci. Techn. 199, 29-40.