An experiment was conducted to eval

An experiment was conducted to evaluate the effects
of a molasses-coated cottonseed product on nutrient digestibility
and milk fatty acid (FA) composition of lactating
dairy cattle. The effect of a direct-fed microbial
(DFM) product was also examined. Twelve Holstein
cows (693 ± 85 kg of body weight, 127 ± 39 d in milk,
2.08 ± 0.29 lactations; mean ± SD) were randomly
assigned to sequence in a replicated 4 × 4 Latin square
design balanced for carryover effects. Cows were fed 1
of 4 treatments during each of the four 14-d periods: a
control diet including 11.4% (dry matter basis) reginned
cottonseed (CON), a diet with 14.4% molasses-coated
cottonseed to match the cottonseed inclusion rate of
the control diet (TC), the control diet with the addition
of a liquid form of the cotton coating used to produce
molasses-coated cottonseed (LC), and the LC diet with
the addition of a DFM (LC+DFM). Diets were formulated
for equal concentrations of neutral detergent
fiber, crude protein, ether extract, and macrominerals.
Treatments had no effect on dry matter intake, apparent
total-tract nutrient digestibility, or milk production.
The molasses coat, in either form, tended to decrease
concentrations of odd-chain FA (2.25 and 2.31 vs. 2.35
g/100 g of FA for TC, LC, and CON, respectively)
and unsaturated FA (31.4 and 31.1 vs. 32.1 g/100 g of
FA) in milk. This could be indicative of a mild shift in
ruminal fermentation away from propionate-producing
bacteria toward fiber-digesting bacteria responsiblefor biohydrogenation of FA. The form of the molasses
coating had few effects, but LC significantly decreased
concentrations of total trans-C18:1 (2.04 vs. 2.30 ± 0.13
g/100 g of FA) and polyunsaturated FA (4.81 vs. 5.01
± 0.17) compared with TC, implying that the liquid
form slightly enhanced ruminal FA biohydrogenation.
Furthermore, adding the DFM to the LC diet tended to
increase the proportion of long-chain FA (FA >C16) and significantly increased the proportions of trans-C18:1
(2.22 vs. 2.04 ± 0.13 g/100 g of FA) and unsaturated
FA (32.4 vs. 31.1 ± 0.7 g/100 g of FA), suggesting an
inhibitory effect on ruminal biohydrogenation. Results
suggest that coating cottonseed with a hardened molasses
product does not significantly depress nutrient
digestibility and may provide a convenient method of
incorporating these ingredients into dairy rations.
Key words: molasses , cottonseed , dairy cattle , directfed
microbial