BY MORRIS THOMPSON
 Herald World Staff

 MEXICO CITY -- Many tequila drinkers like to knock it back with a bit of salt. Now
 the labels on many premium tequila bottles need to be read with a few grains of
 salt, too.

 That's because soaring prices for the agave cactus used to make tequila are
 prompting many distillers to cut the amount of distilled agave in some of their top
 labels from 100 percent to as low as 51 percent, supplemented by other distilled
 sugars.

 Premium prices for these once-premium tequilas haven't dropped. Rather, their
 labels have dropped the words ``100 percent agave'' and say just ``tequila.''

 Aficionados disdain the new brew, calling it ``blended tequila.'' Less expensive
 brands, whose labels have always said just ``tequila,'' haven't changed.

 ``The 51 percent stuff is what most Americans drink, and it's bad,'' sniffed
 veterinary science Professor Antonio Verdugo as he sampled one of his favorites
 in La Tequilera, a restaurant and bar that carries 66 tequilas.

 ``But a connoisseur knows that really good tequila is 100 percent agave,'' he said.
 ``I read the labels on everything, and I've had to stop drinking some tequilas that
 used to be good. It's sad.''

 Ramon Valdés, president of Tequila Herradura S.A. de C.V., Mexico's
 second-oldest commercial tequila distiller, is not happy. His firm came in for
 criticism recently after a reporter noticed that the label on its El Jimador brand
 now says just ``tequila.'' It used to be 100 percent agave.

 Valdés says his company made the change in El Jimador's formula last May.
 Otherwise, he said, his firm would have had to double El Jimador's price, about
 $13 a bottle in Mexico, because agave prices have risen 3,000 percent since
 1995. That's when U.S. demand started to surge and just as it did, a freeze and
 disease cut agave crops sharply.

 Premium brands that have changed their formulas -- and labeling -- include 100
 Años, La Querencia, Tahona, Puente Viejo, Corralejo, Jornalero and Quitapenas.

 The 100 percent agave tequilas accounted for one-fourth of the industry's output of
 181.6 million liters last year.

 Americans consumed slightly more of the total production than Mexicans.
 Mexico's Tequila Regulatory Council doesn't know how much of the exported
 product was pure agave and how much was the 51 percent variety.

 Valdés and others say the pricier premium brands tend to be exported to the
 United States.