Milk production and quality from ewes grazing a plantain-chicory mixture or a grass-based permanent sward

Abstract

Fat lamb production systems in humid-temperate regions rely heavily on grass-based permanent swards with a seasonal growth pattern: scarce in winter, copious in spring and slow or nil growth in dry summers. Plantain (Plantago lanceolata L.) and chicory (Cichorium intybus L.) are summer-active, tolerate water deficit and present a high nutritional quality. They start to grow in late winter (especially plantain) and can be grazed in mid-lactation by ewes suckling their lambs. This work compared milk production and quality of suckling ewes grazing a mixture of plantain-chicory (PCH) or a grass-based permanent sward (GBS) by early spring in two consecutive years. Nine Austral ewes (a local meat breed) in their 8th week post-partum were allocated to PCH and GBS treatments with three replications in two consecutive years. After a pre-experimental period, milk production was determined by the oxytocin method. Milk samples were obtained in the second year and analysed for fat, protein, total solids and urea. Pastures were sampled and analysed for nutritional composition. No effects of treatments were detected for milk production (average 1.43 L/d). PCH milk had lower total solids than GBS milk (19.57 vs. 21.80%, P < 0.01), lower fat (6.97 vs. 9.60%, P < 0.01) and lower urea (47.00 vs, 58.22 mg/100 g, P < 0.05), but protein concentration was higher for PCH than GBS milk (5.71 vs 5.18%, P < 0.05). In forage, total ash was higher (P < 0.05) in PCH than GBS (125.8 vs. 89.9 g/kg dry matter, DM), but lower in year 2016 than 2015 (97.9 vs. 117.7 g/kg DM, respectively). Differences (P < 0.05) were found between swards for NDF (PCH: 245.6; GBS: 394.1 g/kg DM) and years (2015: 372.3; 2016: 267.3 g/kg DM). Apparent DM intake was similar (P > 0.05) between years and swards, averaging 2.15 and 1.78 kg/d for PCH and GBS, respectively. It is concluded that plantain and chicory can be grazed by suckling ewes in mid-lactation without detrimental effects on their milk production or composition.