Dairy cow feeding system alters the characteristics of low-heat skim milk powder and processability of reconstituted skim milk

Abstract

Low-heat skim milk powder (LHSMP) was manufactured on 3 separate occasions in mid lactation (ML, and late lactation (LL, September 27 to October 7) from bulk milk of 3 spring-calving dairy herds on different feeding systems: grazing on perennial ryegrass (Lolium perenne L.) pasture (GRO), grazing on perennial ryegrass and white clover (Trifolium repens L.) pasture (GRC), and housed indoors and offered total mixed ration (TMR). The resultant powders (GRO-SMP, GRC-SMP, and TMR-SMP) were evaluated for composition and color and for the compositional, physicochemical, and processing characteristics of the reconstituted skim milk (RSM) prepared by dispersing the powders to 10% (wt/wt) in water. Feeding system significantly affected the contents of protein and lactose, the elemental composition, and the color of the LHSMP, as well as the rennet gelation properties of the RSM. The GRO and GRC powders had a higher protein content; lower levels of lactose, iodine, and selenium; and a more yellow-green color (lower a* and higher b* color coordinates) than TMR powder. On reconstitution, the GRO-RSM had higher concentrations of protein, casein, and ionic calcium, and lower concentrations of lactose and nonprotein nitrogen (% of total N). It also produced rennet gels with a higher storage modulus (G′) than the corresponding TMR-RSM. These effects were observed over the combined ML and LL period but varied somewhat during the separate ML and LL periods. Otherwise, feeding system had little or no effect on proportions of individual caseins, concentration of serum casein, casein micelle size, casein hydration, heat coagulation time, or ethanol stability of the RSM at pH 6.2 to 7.2, or on the water-holding capacity, viscosity, and flow behavior of stirred yogurt prepared by starter-induced acidification of RSM. The differences in the functionality of the LHSMP may be of greater or lesser importance depending on the application and the conditions applied during the processing of the RSM.

Compositional and functional properties of milk and dairy products derived from cows fed pasture or concentrate‐based diets

“…However, in spite of these compositional differences, Gulati, Hennessy, et al. (2019) did not observe significant differences in the gelation time or gel strength (storage modulus) of yogurts produced from reconstituted skim milk powder made from milk from each feeding system, suggesting that the differences in protein content were insubstantial relative to the natural variation in starter culture activity and fermentation rates between replicates. However, Magan, Tobin, et al.…”

“…Gulati, Hennessy, et al. (2019) found higher levels of Ca ++ in reconstituted low‐heat skim milk powder produced from GRS, than those produced from CLV and TMR, but did not observe any significant variation in HCT between the samples, suggesting that the increased protein and Ca ++ content of the GRS sample may be offset by its reduced lactose content. Reid et al.…”

“…The ethanol stability of GRS, CLV and TMR‐derived skim milk was compared by Gulati, Hennessy, et al. (2019), who did not observe any significant differences in stability between the samples. Similarly, Machado et al.…”

“…Dietary‐based interventions have been widely investigated and have highlighted significant implications for milk product processability (Barłowska et al., 2012; Gulati, Hennessy, et al., 2019), traceability (Coppa et al., 2012; O′Callaghan et al., 2018) and sensory (Bendall, 2001; Clarke et al., 2019; Kilcawley et al., 2018) and nutritional quality (Benbrook et al., 2013; Kelly et al., 1998; O′Callaghan, Hennessy, et al., 2016). Considering this, the objective of this review is to outline the effect of bovine feeding systems on the composition and functional properties of a variety of milk products, with a particular focus on perennial ryegrass, perennial ryegrass/white clover, and indoor TMR‐based systems.…”

Grazing of Dairy Cows in Europe—An In-Depth Analysis Based on the Perception of Grassland Experts

“…• Higher content of unsaturated fatty acids in milk [28][29][30] • Superior processibility qualities [31,32] • Milk quality can be more variable due to the variability of grass supply and quality. This can impact the production of milk products, e.g., cheese yield…”