Effects of misty‐fan cooling and supplemental rbST on rumen function and milk production of crossbred Holstein cattle during early, mid and late lactation in a tropical environment

Abstract

Two groups of five crossbred 87.5% Holstein cattle were housed in normal shade only (NS) as non-cooled cows and in shaded housing with misty-fan cooling (MF) as cooled cows. The cows were treated with recombinant bovine somatotropin (rbST) in early, mid and late lactation with three consecutive injections of rbST in every 14 days. Ambient temperatures and the temperature humidity index in the NS barn were significantly higher than those of the MF barn, whereas relative humidity in MF was higher than that of NS barn. The DMI of cooled cows were higher than those of non-cooled cows, and cooled cows exhibited more response to rbST treatment. Exogenous rbST significantly increased milk yield throughout lactation. The rbST-treated cows had higher total ruminal fermentation products as volatile fatty acid and ammonia nitrogen than the non-rbST treated cows and associated changes were greater in cooled animals in all stages of lactation. Exogenous rbST increased the concentrations of milk urea nitrogen in both groups. These results suggest that the changes in ruminal fermentation with greater production of total VFA and NH(3)N in response to rbST in crossbred cows whether under misty-fan cooling or not, is in part through an increase in feed intake, thereby making more substrate available to the mammary gland for milk synthesis.

Performance and welfare of high-yielding dairy cows subjected to 5 or 8 cooling sessions daily under hot and humid climate

“…Various cooling mechanisms were reported as mitigating adverse effects of heat stress on physiological parameters and yields of dairy cows (Flamenbaum et al, 1986;Her et al, 1988;Smith et al, 2006a;Chanchai et al, 2010). However, although advances in environmental cooling systems ameliorate production losses during summer, heat stress continues to cost the dairy industry (Wheelock et al, 2010).…”

Discovery of Gene Sources for Economic Traits in Hanwoo by Whole-genome Resequencing

“…A list of genes for milking metablism are growth hormone (GH), such as GH1 (1 sSNP), IGF1 (39 sSNPs), and IGF2 (2 sSNPs), prolactin (PRL, 3 sSNPs), LARGE like-glycosyltransferase (687 sSNPs), diglyceride acyltransferase (DGAT1, 2 sSNPs), alpha-lactalbumin (LALBA, 4 sSNPs), lactoferrin (LTF, 53 sSNPs) and signal transducer and activator of transcription 5A (STAT5A, 13sSNPs) (Supplementary Table 2). GH1 has significant positive effect on milk yield throughout lactation (Chanchai et al, 2010). The short isoform of prolactin (PRL) receptor has a suppressive role in PRL signaling to production of milk protein (Berlanga et al, 1997).…”

Exogenous bovine somatotropin and mist-fan cooling synergistically promote the intramammary glucose transport for lactose synthesis in crossbred Holstein cows in the tropics

“…Average values were considered to be the mean of all measurements taken for each date. Temperature humidity index (THI) was calculated according to the National Research Council's equation [10], as follows: THI=0.72 (Tdb+Twb)+40.6, where Tdb is the dry bulb temperature (°C) and Twb is the wet-bulb temperature (°C).…”

“…Considering the obtained data, it was previously hypothesized by our group that a lower environmental temperature that modulates bST action would upregulate milk production in crossbred dairy cows in the tropics. Indeed, the effects of mistfan (MF) cooling combined with recombinant rbST treatment on milk production in crossbred HF cows were shown to involve changes in both intra-and extra-mammary parameters, where 87.5% HF cows housed under MF cooling showed a reduction in the negative effect of high temperatures on digestive function through an increase in the digesta passage rate, resulting in increased feed intake in the supply of nutrients to the mammary gland [10]. The increased dry matter intake (DMI) in response to the combined MF system and rbST treatment was attributed to increased rumen fermentation with consequential increases in the levels of available volatile fatty acids, NH 3 N, and microbial proteins [10].…”

“…Indeed, the effects of mistfan (MF) cooling combined with recombinant rbST treatment on milk production in crossbred HF cows were shown to involve changes in both intra-and extra-mammary parameters, where 87.5% HF cows housed under MF cooling showed a reduction in the negative effect of high temperatures on digestive function through an increase in the digesta passage rate, resulting in increased feed intake in the supply of nutrients to the mammary gland [10]. The increased dry matter intake (DMI) in response to the combined MF system and rbST treatment was attributed to increased rumen fermentation with consequential increases in the levels of available volatile fatty acids, NH 3 N, and microbial proteins [10]. The rbST-treated cows housed in an MF barn showed a high level of water absorption through the ruminal wall, which would in part account for the increased total body water level during rbST treatment [11].…”