114. Effect of grazing and feeding management on milk mineral concentrations

Stergiadis, S. ORCID: https://orcid.org/0000-0002-7293-182X, Qin, N., Faludi, G., Beauclercq, S., Pitt, J., Desnica, N., Petursdottir, A., Newton, E., Angelidis, A., Givens, I. ORCID: https://orcid.org/0000-0002-6754-6935, Gunnlaugsdottir, H. and Juniper, D. (2021) 114. Effect of grazing and feeding management on milk mineral concentrations. In: British Society of Animal Science Annual Conference, 12-15 April 2021, Online, p. 93. doi: 10.1016/j.anscip.2021.03.115

Abstract/Summary

Application. Pasture intake and non-Holstein genetics were negatively correlated with milk I, Mn, and Cu, and positively correlated with milk Ca and P; but other feeds and mineral supplementation also influenced milk mineral concentrations. Introduction. Milk is a good source of minerals (Ca, Mg, P and K) and trace elements (I, Se, Zn), which are essential for optimum health [2]. Pasture intake may increase milk Ca and P concentrations but decrease Cu and Se concentrations, although pasture composition, plant maturity, and animal/environmental factors will also have an effect [1]. This study aimed to (i) investigate the milk mineral concentrations in herds with different pasture intakes, and (ii) assess the relative impact of individual feeds. Material and methods. Bulk-tank milk samples (n = 359) were collected monthly (over 12 months) from 30 dairy farms, and animal diet and breed were gathered via questionnaire. Three groups of 10 farms represented contrasting grazing management between April-September: high pasture intake (HP; 28–65% DMI), standard pasture intake (SP; 5–18% DMI), outdoors with low/limited pasture intake (LP; 0–3% DMI). Milk mineral concentrations were determined using ICP-MS. Analysis of variance by linear mixed effects models used pasture intake (HP, SP, LP), months (12 months), and their interaction as fixed factors. Farm ID was used as a random factor. A multivariate redundancy analysis (RDA; CANOCO 5) assessed the relative impact of breed and feeds on milk mineral concentrations. Results. When compared with HP and LP farms, milk from SP farms contained significantly less Ca (−50 mg/kg and −45 mg/kg, respectively) and P (−25 mg/kg and −29 mg/kg, respectively) (Table 1). The RDA indicated that pasture intake and non-Holstein genetics were negatively correlated with milk I, Mn, and Cu, and positively correlated with milk Ca and P. Grass/grass-clover silage and dry-straights were positively correlated with I, Mn, Cu, Mo, Zn and negatively correlated with Na. Intakes of maize silage, blends, moist by-products, oils and minerals were negatively correlated with Mn, Cu, Mo, Zn, Ca and P. Milk from low/no grazing periods contained, on average, more I (+21.1%), Mn (19.5%), Cu (+16.9%), Zn (+6.1%) and Mo (+5.5%), than milk produced from the grazing season, although between-month differences were not always significant.

Item Type	Conference or Workshop Item (Paper)
URI	https://reading-clone.eprints-hosting.org/id/eprint/97627
Item Type	Conference or Workshop Item
Refereed	Yes
Divisions	Life Sciences > School of Agriculture, Policy and Development > Department of Animal Sciences > Animal, Dairy and Food Chain Sciences (ADFCS)- DO NOT USE
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