This study evaluated the effect of roughage:concentrate (R:C) ratio associated with a variable particle size of physically effective neutral detergent fibre (peNDF8) in the forage (Tifton-85 hay) on the performance, carcass traits and meat quality of lambs. Seventy-two 4-month-old, non-castrated Santa Ines male lambs (23.5 ± 2.32 kg BW) were distributed in a completely randomized design, in a 2 × 2 factorial arrangement [two peNDF8 hay particle sizes (13 and 6 mm) and two R:C ratios (700:300 and 500:500 g/kg DM total)]. DMI, DM, NFC and TDN digestibility's, N-intake and N-faecal excretion were affected by the R:C ratio (P < 0.05). However, the N-retained was not affected by the studied variables (P > 0.05). It was observed an interaction (P < 0.05) between the peNDF8 and R:C ratios for final BW, average daily gain (ADG), colour parameters and pH 24 h. The lower roughage ratio provided greater (P < 0.05) concentrations of C14:1, C16:1–cis9, C18:1–cis9, ΣMUFA, Σn–6:Σn–3 and hypocholesterolemic/hypercholesterolemic index, enzymatic activity Δ9desaturase-C16 and -C18. Lambs fed a lower roughage diet had improved performance and feed efficiency, however, presented reduced polyunsaturated fatty acids (PUFA) concentrations in the meat, especially Σn–3 family. Higher roughage diet and larger peNDF8 particle size improved the concentrations of PUFA while decreased Σn–6:Σn–3 ratio in meat. Larger peNDF8 particle size associated with higher roughage proportion, have reduced animal performance however, it increased protein concentration, a* and C* colour parameter without affecting fatty acids profile of Longissimus lumborum muscle.

The two most important quality attributes for poultry meat are appearance and texture. Appearance is critical for both the consumers' initial selection of the product as well as for final product satisfaction. Texture is the single most important sensory property affecting final quality assessment. Appearance quality attributes include skin colour, meat colour, cooked meat pinkness, and appearance defects such as bruises and haemorrhages. Since appearance is so critical for consumer selection, poultry producers go to great lengths to produce products with the appropriate colour for a particular market and to avoid appearance defects which will negatively effect product selection or price. Historically, meat tenderness was primarily associated with live bird quality factors such as breed, sex, or age. However, modern production practices produce highly uniform young birds in which the major problems associated with meat texture are the result of processing errors or early deboning. Although other quality issues such as juiciness and flavour are important, they are more a function of product preparation and infrequent, but acute, production or processing errors which are usually easily corrected or avoided. An understanding of the major issues contributing to poultry colour and meat tenderness is critical to producing uniform quality products.