Impact of diet composition and temperature–humidity index on water and dry matter intake of high‐yielding dairy cows

Abstract

SummaryThe temperature-humidity index (THI) is widely used to characterize heat stress in dairy cattle. Diet composition is known to induce variation in metabolic-associated heat production. However, the relationships between THI and diet are poorly characterized with regard to performance and intake behaviour. Therefore, the objectives were to evaluate the impact of THI on water intake (WI), dry matter intake (DMI) and the frequency of drinking and feeding bouts in lactating dairy cows offered four dietary treatments: each contained 20% grass silage and additionally (i) 20% maize silage, 60% concentrate (M-HC); (ii) 60% maize silage, 20% concentrate (M-LC); (iii) 20% pressed beet pulp silage, 60% concentrate (BPS-HC); or (iv) 60% pressed beet pulp silage, 20% concentrate (BPS-LC) (DM basis). Individual WI and DMI were recorded from April to July 2013. Furthermore, dietary effects on milk production and reticular pH were estimated. Milk yield was lowest for M-LC, while energy-corrected milk was similar for all diets. Milk fat percentage was higher and milk protein amount lower for cows offered both LC diets. Reticular pH below 6.3, 6.0 and 5.8 lasted longest for BPS-LC. WI was higher for HC diets. However, the frequency of drinking bouts was not influenced by the ration. Lower DMI occurred for BPS-LC compared to M-LC. Frequency of feeding bouts was significantly higher for LC diets. THI was significantly related to WI, DMI as well as drinking and feeding bouts. Per increasing THI, WI increased slightly more for LC diets and DMI decreased more for HC diets. Frequency of drinking bouts increased slightly higher for BPS rations per rising THI, while the decrease in feeding bouts was highest for M-HC. In conclusion, TMR composition and moderate heat stress impacted WI and DMI of dairy cows, while both dietary energy density and ruminal filling might intensify the THI impact.

Nutritional Physiology and Biochemistry of Dairy Cattle under the Influence of Heat Stress: Consequences and Opportunities

“…When ambient temperature exceeds 25 • C, cattle experiences HS [7]. Traditionally, temperature-humidity index (THI) is used to assess HS in dairy production [8][9][10]. THI calculations are based on dry (Tdb in • C) and wet bulb temperatures (Twb in • C)/relative humidity (RH in %).…”

“…THI has been successfully employed to asses HS in the dairy cattle at various conditions of indoor or outdoor [13] different climate and production systems [14,15]. The common consensus about THI scale is the upper threshold THI, upon which the cow starts to experiences signs of hyperthermia [7,10]. This threshold has been reported variable upon different systems, generally started from 67 [16] and 72 [5,17], THI above these limits initiated hyperthermia derived discomfort [15], altered physiology [11], decreased feed intake [18], and decline in milk yield and composition [19].…”

Effects of the combination between selected phytochemicals and the carriers silica and Tween 80 on dry matter and neutral detergent fibre digestibility of common feeds

“…The fermentations were repeated twice in two separate weeks. The PCs were combined with the carriers at the equivalent dose of 1 g/cow/day, as suggested by Benchaar et al (2006), assuming a hypothetical DM intake of about 20 kg (Righi et al 2017;Ammer et al 2018). The final concentration of the PCs in each flask was therefore set at 50 mg kg À1 of DM (equivalent to 0.5 mg L À1 considering a substrate of 0.5 g and 50 ml of liquids in each flask).…”

Review: Challenges for dairy cow production systems arising from climate changes

“…Heat stress is also detectable by behavioral alterations such as a reduction and/or changes in activity (Cook et al, 2007), increased water intake, reduced feed intake (Ammer et al, 2017) or a shift in feed intake to colder times of the day. Allen et al (2015) described changes in standing and lying behavior of heat-stressed dairy cattle what might further decrease obvious estrus signals such as mounting.…”