Cattle slaughter during the first 9 months of 1965 was 5 percent larger than a year earlier. But the output of carcass beef was up only 1 percent -- reflecting lighter market weights on fed cattle and more cows and heifers in the slaughter. October marketings continued above last year. Indications are that slaughter for the October-December quarter will be 6 to 8 percent above a year earlier.