Heat stress, intensified by climate change, significantly decreases food consumption in infants, affecting their well -being, milk production and reproductive performance. This reduction in energy intake forces it to mobilize body reserves. To mitigate these effects, strategies such as diets with lower thermogenic effect or adjustments in feeding schedules are proposed to avoid the warmest hours. Thus, two independent tests were carried out in controlled conditions to evaluate the impact of different nutritional strategies (normal diet and less thermogenic diet) and food management in infant sows exposed to chronic thermal stress (E1) or acute (E2).
Materials and methods
144 bristles were used (Large White × Landrace), distributed in 6 groups of 24 animals each. The study was divided into two essays:
- Test 1 (E1): The sows were exposed to chronic thermal stress (constant 25 ° C) throughout breastfeeding, which lasted 28 days.
- TEST 2 (E2): Food strategies were not applied throughout breastfeeding; Instead, they adjusted according to temperature conditions.
At the beginning of E2, all sows received the TEM. Then, depending on the weather, different strategies were applied: if high temperatures were foreseen and 25 ° C were already reached in the room, the feed was modified from 5 in the afternoon and maintained throughout the heat wave, even for 2 or 3 more days. When the heat wave ended, the normal treatment (TEM) was used again until a period of extreme temperatures returned.
The treatments evaluated were:
- T1 – TEM: Standard diet (9.5 MJ at/kg; 73.6 % in/EM)
- T2 – Ali: less thermogenic diet (10.3 mj en/kg; 76.3 % en/em)
- T3 – DIS: TEM diet, supplied at times that avoided the highest heat hours.
Variables such as the consumption of net food and energy, weight loss, dorsal fat thickness (EGD) and dorsal muscle (EMD), litter growth and consumption distribution at different food hours.
Results
Chronic stress (E1): The sows of the ALI treatment consumed more in (61.3 mj/d) compared to DIS (49.7 mj/d) and TEM (51.4 mj/d) (p = 0.001). This greater intake in Ali also reduced the loss of dorsal muscle (EMD: -2.8 mm, equivalent to -3 %) compared to DIS (-9.2 mm, -15 %) and TEM (-7.1 mm, -11 %); P = 0.007), without significantly affecting living weight loss or dorsal fat.
Acute stress (E2): The sows of the ALI treatment (60.3 mj/d) and dis (57.0 mj/d) consumed more than TEM (48.5 mj/d) (p = 0.004). The consumption of dry matter was also greater in Ali and DIS (p = 0.004). However, there were no significant differences in the mobilization of body reserves (living weight, dorsal muscle thickness and dorsal fat) between the groups. The sows of DIS treatment moved part of their consumption to cooler hours during heat waves.
The performance of the piglets did not differ between the treatments in both trials.
Table 1: Summary of key sows performance results
| Parameter | E1 (Chronic stress) |
E2 (Acute stress) |
||||
|---|---|---|---|---|---|---|
| TEM | DIS | ALI | TEM | DIS | ALI | |
|
Dry matter consumption
|
5,41a | 5,23A | 5,95b | 5,11a | 6,00b | 6.10b |
|
Net energy consumption
|
51,4A | 49,7A | 61.3B | 48,5a | 57,0b | 60.3B |
|
Dorsal muscle thickness loss (EMD), %
|
-11a | -15a | -3b | -15 | -9 | -10 |
|
Live loss
|
-16 | -15 | -13 | -16 | -13 | -14 |
|
Dorsal fat thickness loss (EGD), %
|
-23 | -25 | -21 | -27 | -24 | -23 |
Abbreviations: Tem = Control, Dis = TeMs with supply of ration during different hours, ali = less thermogenic diet. EMD = dorsal muscle thickness, PV = living weight, EGD = dorsal fat thickness. Different letters (a, b) in the same row and within the same trial indicate significant differences (p <0.05 or P <0.01 according to the original article). The values without letters for EMD, PV and EGD in trial 2 showed no significant differences (p> 0.05).
Discussion
The study confirms the negative impact of thermal stress, both chronic and acute, on the consumption of ration in infants, and validates nutritional and management strategies to mitigate it. The conclusion on the effect of heat stress on food consumption was based on the comparison of the growth of the litters with the observed during other stations, since no bristles were included under thermoneutral conditions in this study.
The less thermogenic diet (ALI) consistently increased the intake of in under both stress conditions, contributing to preserve dorsal muscle during chronic stress.
For its part, the Modification of food supply schedule (DIS), avoiding the hottest hours of the day, allowed to increase the intake of in only during heat waves (acute stress), without effect under chronic stress conditions. This suggests that the benefit of the schedule adjustment is greater when thermal stress is transitory, since it facilitates a displacement of consumption towards the coolest periods of the day.
In conclusion, Both strategies are valid tools. The less thermogenic diet (ALI) offers more consistent benefits against different thermal stress scenarios. The modification of schedules (DIS) is effective in front of specific heat waves, but its implementation depends on having sufficiently flexible power systems. The choice between different strategies will depend on the type of predominant thermal stress and farm infrastructure.
Content prepared by Drafting 333, as a summary of: “Is it enough to use a less thermogenic food or avoid the distribution of meals during the hottest hours of the day to improve the energy ingested of the breastfeeding sow exposed to chronic or punctual thermal stress?”
Nathalie Quiniou (1), Julie Dupuis (1), David Renaudeau (2)
(1) IFIP – Institut du Porc, 9 boulevard du Trieux, 35740 Pacé, France
(2) STICKS, INRAE, AGRO INSTITUTE,
