F5 Networks forecasts adjusted profit above estimates Wed Jan 23, 2013 4:55pm EST (Reuters) - Network gear maker F5 Networks Inc (FFIV.O) reported lower-than-expected quarterly results on a slowdown in federal sales, but forecast second-quarter adjusted profit above analysts' estimates. The company on Wednesday forecast adjusted earnings of between $1.21 and $1.24 per share for the quarter ending March 31. Analysts on average were expecting $1.20 per share in earnings, according to Thomson Reuters I/B/E/S. Net income rose to $69.5 million, or 88 cents per share, for the first quarter from $66.5 million, or 83 cents per share, a year earlier. The company, which counts Cisco Systems Inc (CSCO.O), Juniper Networks Inc (JNPR.N) and Riverbed Technology Inc (RVBD.O) as rivals, earned $1.14 per share, excluding items. Revenue for the quarter rose 13 percent to $365.5 million. "During the first quarter, strong sales to North American enterprises and service providers were offset by a substantial slowdown in U.S. Federal sales," Chief Executive John McAdam said. Analysts expected earnings of $1.15 per share on revenue of $366.7 million. F5 shares were up 5 percent at $104 in extended trading. They closed at $98.81 on the Nasdaq on Wednesday. Reporting by Sruthi Ramakrishnan in Bangalore; Editing by Joyjeet Das