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

Nutritionists have access to various ingredients that fulfill methionine (Met) requirements of broilers. Amino acids (AA), such as DL-methionine, are nearly 100% bioavailable while methionine hydroxy analogs are shown to be relatively less bioavailable.

Thus, this experiment aimed to determine the efficacy of using a 65% DL-methionine and 35% limestone dilution product (65DLM) compared to a methionine hydroxy analog (MHA) product when included in a diet deficient in total sulfur AA. A total of 3,072 Ross 708 male broilers received diets varying in Met source (none, MHA, or 65DLM) and crude protein (CP) (Standard or Reduced 2%).

Treatments were arranged in a 2 x 3 factorial in a randomized complete block design. Each treatment was fed to 16 replicate floor pens with 32 broilers/pen across a 3-phase feeding program from d1-42. Broiler performance was measured during the starter (d1-10), grower (d11-24), finisher (d25-42), and overall (d1-42) periods. On d 24 and 42, litter was collected to determine litter moisture and three birds/pen were selected for footpad lesion scoring (FLS). On d42, three broilers +/- 10% of the average pen weight were selected for processing yield.

Performance, litter moisture, and processing metrics were analyzed by two-way ANOVA using the GLM procedure of SAS. FLS were analyzed via descriptive statistics by using the frequency procedure of SAS. Broilers receiving Standard CP (SCP) with either MHA or 65DLM consumed 1,676 g more feed and gained 1,300 g more than Reduced CP (RCP) with no Met during d1-42 (P< 0.001).

Additionally, a d1-42 FCR interaction indicated a 0.3 FCR improvement (P=0.007) for broilers consuming SCP with either MHA or 65DLM compared to broilers consuming RCP with no Met. Overall, RCP-fed birds, regardless of Met source, showed reduced performance than their counterpart SCP treatments. At d24 and d42, both main effects impacted litter moisture (P< 0.05). 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 d42, 23 SCP-fed birds had FLS other than “0” while only five RCP-fed birds had FLS other than “0”. Breast weight was highest when 65DLM was included in SCP diets and reduced when MHA was provided in either RCP or SCP diets. Breast weight was intermediate when 65DLM was provided in RCP diets and were lowest when Met was not supplemented in RCP diets (P=0.003). Overall, this experiment indicates that 65 parts of DLM can replace 100 parts of MHA in formulation where broilers maintained performance and improved breast weight.

KEYWORDS: footpad lesion, methionine, broilers, crude protein, litter moisture

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