Abstract
High-yielding dairy cows experience a negative energy balance and inflammatory status during the transition period. Fat supplementation increases diet energy density, and plasma n-3 polyunsaturated fatty acids (PUFA) have been proposed to improve immune function. This study tested the hypothesis that dietary supplementation with a rumen-protected and n-3 PUFA-enriched fat could ameliorate both the energetic deficit and immune status of postpartum high-yielding dairy cows, improving overall health and reproductive efficiency. At 11 d in milk (DIM), cows were randomly allocated to groups (1) n-3 PUFA (n = 29), supplemented with encapsulated linseed oil supplying additional up to 64 g/d (mean 25 ± 4 g/d) of α-linolenic acid (ALA), or (2) control (n = 31), supplemented with hydrogenated palm oil without ALA content. Fat supplements of the n-3 PUFA and control groups were available through an automated, off-parlor feeding system, and intake depended on the cow's feeding behavior. Plasma ALA concentrations were higher in n-3 PUFA than control cows, following a linear relation with supplement ingestion, resulting in a lower n-6/n-3 ratio in plasma. Metabolic parameters (body condition score and glucose and β-hydroxybutyric acid blood concentrations) were unaffected, but milk yield improved with increased intake of fat supplements. Plasma total adiponectin concentrations were negatively correlated with ingestion of n-3 PUFA-enriched fat supplement, following a linear relation with intake. Conception rate to first AI increased with higher intake of both fats, but a decrease of calving-to-conception interval occurred only in n-3 PUFA cows. Postpartum ovarian activity and endometrial inflammatory status at 45 DIM were unaffected. In conclusion, this study evinced a positive linear relation between rumen-protected linseed fat intake and plasma n-3 PUFA concentrations, which modulated adiponectin expression and improved reproductive parameters.
Highlights
The high-yielding dairy cow transition period is characterized by a state of negative energy balance, which adversely affects cow health, fertility, and milk yield (Raboisson et al, 2014; Abdelli et al, 2017; Sheldon et al, 2019)
N-3, and n-6 polyunsaturated fatty acids (PUFA) increased with d in milk (DIM) (P ≤ 0.001)
Plasma n-3 PUFA concentrations were higher in the n-3 PUFA group than in the control group, increasing (P ≤ 0.001; Table 3) by 0.142 ± 0.026 mg/dL per kilogram of n-3 PUFA supplement ingested, whereas no increase (P = 0.292) was observed in the control group
Summary
The high-yielding dairy cow transition period is characterized by a state of negative energy balance, which adversely affects cow health, fertility, and milk yield (Raboisson et al, 2014; Abdelli et al, 2017; Sheldon et al, 2019). Fat supplementation has become a common strategy to increase the energy density of diets and minimize the effects of negative energy balance (Palmquist and Jenkins, 2017; Bionaz et al, 2020) This may reduce DMI, disturb rumen function, and originate fatty acid (FA) isomers that depress milk fat (Chamberlain and DePeters, 2017; de Souza and Lock, 2019; Manriquez et al, 2019). Because FA, namely PUFA, have essential physiologic roles, the beneficial effects of fat supplementation may rely more on FA type than on increased energy intake (Herrera-Camacho et al, 2011) In this context, the PUFA from n-3 (α-linolenic acid, ALA; eicosapentaenoic acid, EPA; docosapentaenoic acid, DPA; and docosahexaenoic acid, DHA) and n-6 (linoleic acid, LA; and arachidonic acid) families receive special attention due to their roles in reproductive and immune function (Moallem, 2018; Moallem et al, 2020). Increased intake of n-3 PUFA increases the proportion of EPA and DHA in cell membranes, which favors eicosanoid synthesis toward an anti-inflammatory state (Greco et al, 2015; Wolf et al, 2019)
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