Figure 2 - Effects of isoquinoline alkaloid supplementation (IQs; blue solid line) on lactating dairy cows milk yield (A), log somatic cell count (Log SCC; B), and milk yield during the hot (C; from March 20th until September 22nd) and cold (D; from September 23rd to March 19th) seasons relative to un-supplemented control cows (CON; pink dashed line; adapted from Audonnet et al., 2020).
23 25 27 29 31 33 35 37
A
23 25 27 29 31 33 35 37 39
C IQs CON
TRT: 0.0005 TIME: <.0001 TRT*TIME: 0.84
Test 1 Test 2 Test 3 Test 4 Test 5 IQs Test 6 CON B
TRT: 0.0005 TIME: <.0001 TRT*TIME: 0.84
Test 1 Test 2 Test 3
*P< 0.05; **P > 0.05 < 0.01 #Test 1-6 refer to monthly official tests.
Test 4 Test 5 Test 6 D
23 25 27 29 31 33 35 37 39
3.5 4.0 4.5 5.0 5.5
Test 1 IQs CON
TRT: 0.0005 TIME: <.0001 TRT*TIME: 0.84
Test 2 Test 3 Test 4 Test 5 IQs Test 6 CON
TRT: 0.0005 TIME: <.0001 TRT*TIME: 0.84
Test 1 Test 2 Test 3 Test 4 Test 5 Test 6
and tight junction integrity with the resulting loss of intesti- nal barrier integrity. Loss of barrier integrity leads to in- creased intestinal permeability, which allows the passage of endotoxins leading to the activation of the immune system and systemic inflammation. In addition, due to the reduc- tion of FI, HS cattle ruminate less which results in less buff- ering agents entering the rumen; this can predispose them to acidosis and further damage of the intestinal barrier and inflammatory response. Thus, nutritional strategies that pre- serve intestinal barrier integrity and promote FI of HS dairy cattle are critical.
A natural strategy Natural feed additives containing isoquinoline alkaloids (IQs) have been extensively used in food-producing animals. These alkaloids with documented mode of action on the di- gestive system promote FI and support the digestibility of nutrients. Consequently, more energy is available for maintenance and productive processes, which supports performance and contributes to maintenance of overall health. Furthermore, studies in ruminants and other species demonstrated that supplementing IQs under HS conditions mitigates the negative impact of elevated temperatures and humidity. To assess the effects of IQs supplementation on ruminal in- flammation and performance under severe HS conditions, Estrada Angulo and others (2016) randomly allocated finish- ing ewes to receive IQs or remain as control. Results showed
that ewes in the IQs group had reduced ruminal inflamma- tion and improved performance when compared to controls (see picture; Figure 1 a,b). More recently, a study conducted in 18 dairy herds in France investigated the effects of IQs supplementation on perfor- mance of lactating dairy cows. Approximately 21 days prior to the expected calving date, dry cows were randomly allo- cated to two treatments. Cows in the control group were fed the basal diet without IQs supplementation, while cows in the treatment group received IQs through the transition pe- riod into mid-lactation. Overall, cows in the IQs group yield- ed more milk and had less somatic cell counts than controls (Figure 2 a,b). Furthermore, an analysis accounting for sea- son of the year was conducted. The cold season was defined as the period from 23 September to 19 March (autumn and winter), while the warm season was defined as the period from 20 March until 22 September (spring and summer). Analysis by season revealed that, although milk yield im- proved during both seasons, a greater positive impact on milk yield was observed during the hot months (milk yield increased by 5.9% in IQs relative to the control group) com- pared to the cold months (milk yield increased by 3.0% in IQs relative to the control group) of the year ( Figure 2 c,d). HS is a major concern affecting food-producing animals globally and strategies to mitigate its negative effects are needed. Supplementing dairy cows with IQs can be regard- ed as an effective strategy to reduce the effects of HS and promote milk yield in lactating dairy cows.
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Milk Yield (L)
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Log SCC
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