Natural tree shade increases milk stability of lactating dairy cows during the summer in the subtropics

Abstract

This research communication addresses the hypothesis that, during the summer in the subtropics, natural tree shade helps to improve milk functional characteristics such as stability and acidity. Sixteen Holstein lactating cows were enrolled. The study consisted of three periods (pre-stress, heat stress and post-stress) based on allocating grazing cows into two treatments (with and without access to shade during the Heat Stress period). Overall THI during the trial was (mean ± se) 76.0 ± 3.4. Access to shade prevented the heat stress-related decrease in milk stability both in the ethanol and in the coagulation time test, as well as maintained milk acidity within an acceptable range (14 to 18°D).

Elevated temperature-humidity index induces physiological, blood and milk alterations in Holstein cows in a more pronounced manner than in 1/2 and 3/4 Holstein × Gir

“…Titratable acidity differed among groups but stayed inside the preconized range (14 to 18ºD) and in the same ascending tendency observed before starting the experiment: H100<H75<H50. In Abreu et al (2020), cows under stress and without shade showed a loss of stability associated with higher titratable acidity. Holstein cattle (H100) are more heat susceptible.…”

The effect of diet restriction on raw milk stability: a meta-analytical approach

“…However, only 27-39% of the variations in milk yield, acidity, protein and lactose concentrations are explained by feed restriction. Authors acknowledge the multifactorial nature of milk stability, reflecting variations in mineral composition (Tsioulpas et al, 2007), acidity and caseins affected by feeding practices (Gabbi et al, 2015(Gabbi et al, , 2018 as well as animal health, breed (Vizzotto et al, 2021), metabolic status (Marques et al, 2011), lactation stage (Marques et al, 2010a) and heat stress (Abreu et al, 2020).…”

Characterization of variables related to high stability of raw cow milk

“…Several factors affect milk stability, including nutrition (Stumpf et al ., 2013), feeding (Pinheiro et al ., 2022), genetics (Davis et al ., 2001), age or number of lactations, lactation stage (Omoarukhe et al ., 2010), environmental factors, mammary gland health including bacterial contamination (Zanela et al ., 2006), methodological factors (Zanela and Ribeiro, 2018), heat stress (Abreu et al ., 2020) and the concentration of ionized calcium (iCa) in milk (Akkerman et al ., 2019). These factors have already been identified and associated with cases of low milk stability on small farms, however, few studies have evaluated the effect of these factors on milk stability in herds with different levels of technical management.…”