Effects of Pasture Allowance on the Yield and Composition of Milk from Cows of Different β-Lactoglobulin Phenotypes

Abstract

The objective of this study was to determine whether the differences in the composition of milk from cows of different beta-lactoglobulin beta-LG) phenotypes are affected by the amount of pasture available and, hence, pasture dry matter intake. Twenty-two Friesian cows of each of the AA and BB variants of the beta-LG phenotype were subjected to ad libitum grazing or restricted grazing in crossover experiments during spring (early lactation, approximately 60 d in milk) and summer (mid to late lactation, approximately 180 d in milk). Milk samples were collected from each cow at the end of each 8-d treatment period and analyzed for composition. Cows of the AA variant of the beta-LG phenotype had higher concentrations of whey protein and beta-LG, but lower concentrations of casein (CN), alpha-CN, kappa-CN (summer only), and BSA, than cows of the BB variant. Compared with cows with a restricted allowance, cows grazing ad libitum had higher milk yields and concentrations of protein, casein, whey protein, and all individual proteins except BSA and immunoglobulin. There were no interactions between effects of pasture allowance and phenotype on milk yield or composition. The data show that having adequate pasture for grazing cows is important not only to maximize milk yield, but also to optimize concentrations of protein and casein, and hence the manufacturing potential of milk. Further, the differences in composition of milk from cows of differing beta-LG phenotypes persisted during short-term restrictions in pasture allowance, and between spring and summer.

Variation of lactoferrin and lactoperoxidase in bovine milk and the impact of level of pasture intake

“…Differences in yields of fat, protein and lactose between the cows in the ad libitum herd and the restricted herd were consistent with the differences in milk yield (12.1 versus 10.6 kg day -1 respectively; Table 3). As reported by Auldist et al (2000), casein protein concentrations were decreased in the milk of cows on a restricted allowance of pasture. Milk yield and protein concentration were decreased in the cows in the restricted herd as was found by Mackle et al (1999a) and Gray & Mackenzie (1987).…”

“…Decreased intake of pasture leads to decreased de novo synthesis of milk proteins, such as casein (Auldist et al 2000). Further, both Gray & Mackenzie (1987) and Mackle et al (1999a) have previously reported that energy intake affects the concentrations of other whey proteins in milk (for example β-lactoglobulin and α-lactalbumin concentrations are decreased in the milk of cows on a restricted feed allowance).…”

Composition of major proteins in cow milk differing in mean protein concentration during the first 155 days of lactation and the influence of season as well as short-term restricted feeding in early and mid-lactation

“…It seems that in HP-cows milk protein synthesis was decreased more than milk yield, leading to a decrease in milk protein concentration. Auldist et al (2000) found significant changes in all individual milk proteins during restricted pasture allowance over 8 days in dairy cows. Bobe et al (2009) observed slightly decreased whey protein concentrations with declining α-LA and increasing β-LG and constant casein concentrations with slightly increased α S1 -CN and decreased α S2 -, β-, and κ-CN concentrations during energy restriction of 20% over 14 days.…”

“…Furthermore, feeding plays an important role in milk protein composition, particularly during the time of the undesirable nadir in milk protein concentration during early lactation (Auldist et al, 2000). Yet, scarce information is available on the influence of energy restriction, season or stress on the composition of all major milk proteins.…”

Determination of Micro minerals in Milk from Farm and Pasture-reared Cow, Goat and Camel; using Inductively Coupled Plasma-Optical Emission Spectrometry

“…Proximate analysis of cow, goat and camel milk showed a protein % of 3.42, 3.26 and 3.26 respectively; a fat content of 4.09, 4.07 and 3.80 respectively and lactose content of 4.82, 4.51 and 4.30 respectively [2][3][4][5][6][7] . Water content of whole cow, goat and camel milk at Kingdom of Bahrain, reported as 87.4, 87.0 and 87.5 %, respectively 8 .…”