SAO PAULO, May 11 (Reuters) - JBS SA, the world's largest meat company, on Thursday reported a net loss of 1.45 billion reals ($290.2 million) for the first quarter, blaming high grain prices and an over-supplied meat market for the worse-than-expected results.

Analysts had expected a 297 million real loss, according to Refinitiv consensus estimates. JBS said adjusted earnings before interest, tax, depreciation and amortization, a measure of operating income known as EBITDA, fell by almost 79% to 2.162 billion reais in the quarter.

The weak results reflect the challenging environment in the United States, where livestock prices are rising and consumers are deterred by high inflation, hurting JBS and rivals like Tyson Foods (TSN.N), which also reported losses this week.

JBS said U.S. cattle prices jumped 16% year- on-year, while wholesale meat prices rose only 2%, eroding margins.

JBS Global CEO Gilberto Tomazoni called the first-quarter results "an exceptional case" and said in an interview JBS had taken measures "to reduce the impacts of circumstances."