Effects of methionine supplement sources and crude protein on Ross 708 male broiler performance and carcass yield

This 42 d experiment investigated the influence of crude protein (CP) levels, methionine (Met) supplement sources, and their interaction on growth performance, processing measurements, footpad lesion scores (FLS), and litter moisture. A total of 3,072 Ross 708 by-product males received diets varying in CP (Standard [SCP] or Reduced 2% [RCP]) and Met sources (None, Methionine hydroxy analog [MHA], or 65% DL-Met [65DLM]). Treatments were arranged in a 2 (CP) x 3 (Met sources) factorial in a randomized complete block design. Each treatment was fed to 16 replicate floor pens with 32 birds/pen across a 3-phase (starter, d 1–10; grower, d 11–24; finisher, d 25–42) feeding program. Performance was measured during d 1 to 10, 1 to 24, and 1 to 42. On d 24 and 42, litter moisture was determined, and 3 birds/pen were selected for FLS. On d 42, 3 birds were selected for processing. Regardless of Met source, RCP-fed birds showed reduced performance compared to birds fed SCP treatments. Birds fed SCP diets increased litter moisture when compared to birds fed RCP diets. Likewise, birds fed either MHA or 65DLM had higher litter moisture content than birds provided a diet with no Met supplementation. On d 42, 90% of FLS across all treatments had a score of “0”. Breast weight was highest when 65DLM was in SCP diets and reduced when MHA was in either RCP or SCP diets. This experiment indicates that 65DLM and MHA can be used interchangeably in formulation, achieving similar performance and improved breast weight with 65DLM in SCP diets.