Figure 1. Average sow backfat during lactation.
S.M. Neal+, K.M. Irvin*, and G.C. Shurson++
+Agricultural Technical Institute,
*Department of Animal Sciences, and
++Department of Animal Science, University of Minnesota, St. Paul
The primary objective of this study was to determine the effects of supplemental dietary fat on sow body weight, sow backfat thickness, sow feed consumption, litter size, and pig growth rate. Dietary treatments included 0, 3, 6, and 9% supplemental low acid yellow fat in a traditional corn-soybean meal basal lactation diet. A total of 160 Landrace and crossbred sows (approximately 40 per treatment) were included in the study. Results indicated that added dietary fat for the lactating sow increased average fat thickness, regardless of supplemental fat level, allowing for improved body condition at the end of the lactation phase. Results for weight change and feed consumption were inconsistent. Results of the pig data indicated that the dietary fat level of the lactating sow did not affect the number of pigs born alive or number of stillborns. However, the 9% fat level was associated with more mummified pigs at birth. Number of pigs weaned was greater for the control group than for the highest fat level. The largest pig weights at 21 and 28 days were those from sows fed the 3% added fat diet.
Research has been conducted using dietary added fat levels for sows ranging from 2 to 40%, and a variety of fat sources have been used. Many experiments have used added fat levels between 7.5 and 15%, and this range has generally resulted in the greatest response in pig survival. The number of pigs weaned per litter appears to be maximized by levels greater than 15% added fat.
Currently, most commercial feeding programs using supplemental fat add between 0 and 10% fat to the ration. These levels are below or at the lower end of the range where the greatest response to fat has been obtained. One of the primary reasons for minimizing the amount of fat added to the diet is economics. The objectives of this study were to determine if providing 3, 6, or 9% added fat from an animal-vegetable source provides enough performance benefit to justify the cost of adding fat compared to sow and litter performance when sows were fed a traditional corn-soybean meal diet.
A total of 160 Landrace and crossbred females were included in this study. Dietary treatments included 0, 3, 6, and 9% low acid yellow fat added to a corn-soybean meal diet (Table 1). Sows were allotted to treatments based on weight, parity, and breed composition. Diets were fed at a rate of 0.45 kg of diet per 45.4 kg of body weight, beginning at day 105 of gestation. Post-farrowing sows were fed ad libitum through a 28-day lactation period. Sows were weighed at 105 days of gestation, at farrowing, and weekly thereafter. Five backfat readings were taken at farrowing and 21 and 28 days of lactation. Feed consumption pre-farrowing and weekly feed consumption post-farrowing was recorded. The weights and the number of piglets born alive were recorded, as well as the number of stillborn, mummified, and laid-on piglets. The weights and the number of pigs at weaning also were recorded.
| Table 1. Percentage dietary composition as fed. | ||||
| Fat level, % | ||||
| Ingredient | 0 | 3 | 6 | 9 |
| Corn | 75.82 | 72.53 | 69.24 | 65.94 |
| Soybean meal (44% CP) | 20.07 | 20.35 | 20.62 | 20.90 |
| Dynafos1 | 2.47 | 2.51 | 2.55 | 2.59 |
| Limestone2 | 0.75 | 0.72 | 0.70 | 0.68 |
| TMS-503 | 0.50 | 0.50 | 0.50 | 0.50 |
| Premix4 | 0.20 | 0.20 | 0.20 | 0.20 |
| Selenium5 | 0.15 | 0.15 | 0.15 | 0.15 |
| Antibiotic6 | 0.05 | 0.05 | 0.05 | 0.05 |
| Fat7 | . . . | 3.00 | 6.00 | 9.00 |
| 1 Contained 18.5% P, 20% min. Ca.
2 Contained 38% Ca. 3 Morton Salt Co., Rittman, OH. Contained 0.214% copper oxide (75%), 11.454% ferrous sulfate (21%), 0.006% calcium iodate (63.5%), 0.502 manganese oxide (60%), 3.304% zinc oxide, 84.42% salt, 1.0% mineral oil. 4 Contained (amount/kg) 1,335,988 IU vitamin A (acetate), 72,752 IU vitamin D3 , 13,360 vitamin E (acetate), 168 mg vitamin K (menadione), 1,345 mg riboflavin, 5.07 g D-pantothenic acid, 3.97 g niacin, 330.69 mg folacin, 66.14 mg biotin, 6.61 mg vitamin B12, 418.87 g choline, 22.05 g BHT (antioxidant), rice hulls carrier to bring total to 1 kg. 5 Contained 200.18 mg/kg. 6 Auromycin 50. 7 Low acid yellow fat, G.A. Wintzer and Sons, Wapakoneta, OH. True Energy Hog Blend: 90% total fatty acid, 15% maximum free fatty acid, 7937 calories/kg, rendering process blend of animal and vegetable oils. | ||||
Sow data were analyzed using a model which included the effects of season, diet, parity, breed of sow, breed of sire, and appropriate covariates. Backfat at farrowing was adjusted to a common weight at farrowing, and backfat at weeks 3 and 4 was adjusted to a common weight and number nursed for that week. The same models were used to analyze backfat loss variables. Weight loss was adjusted for a specific week to a common sow starting weight and litter size nursed. Sow feed intake pre-farrowing and weekly during the lactation phase was adjusted to a common sow weight at the beginning of the feeding period.
Litter data and average pig weights were analyzed with a model which included the effects of season, diet, parity, breed of dam, and breed of sire.
There was no significant difference in backfat among the treatment groups at farrowing (Table 2, Figure 1). However, by the third week of lactation, sows fed diets with 3 and 9% added fat had greater fat thickness than sows fed the control diet. This difference also was observed at the fourth week of lactation. Of interest was the increase in backfat thickness for all groups from week 3 to week 4.
Daily sow weight loss (Table 2, Figure 2) during week 1 was greater for those fed 3% added fat compared to those fed 6% added fat. During week 4, sows fed the 9% added fat diet had greater weight loss than those fed the 3% added fat diet. No other statistical differences were detected among means for the 4 weeks. These results were quite inconsistent and difficult to interpret.
| Table 2. Least squares means for sow average backfat, weight loss, and feed consumption. | ||||||||
| Fat level, % | ||||||||
| Trait | 0 | 3 | 6 | 9 | ||||
| Average sow backfat, mm | ||||||||
| Farrowing | 22.25 ± 1.37 | 22.87 ±1.43 | 22.93 ±1.36 | 21.90 ± 1.31 | ||||
| Week 3 | 19.12 ±1.15a | 20.45 ±1.15b | 20.48 ±1.15b | 20.39 ±1.12 | ||||
| Week 4 | 19.47 ±1.03a | 20.66 ±1.05b | 20.66 ±1.02b | 20.51 ±1.00 | ||||
| Daily sow weight loss, kg | ||||||||
| Week 1 | - 0.53 ±0.30a | - 0.62 ±0.31a | - 0.12 ±0.29b | - 0.37 ±0.29 | ||||
| Week 2 | - 0.30 ±0.26 | - 0.35 ±0.27 | - 0.28 ±0.26 | - 0.42 ±0.25 | ||||
| Week 3 | - 0.48 ±0.24 | - 0.61 ±0.24 | - 0.43 ±0.24 | - 0.47 ±0.22 | ||||
| Week 4 | - 0.21 ±0.28 | - 0.07 ±0.28a | - 0.17 ±0.28 | - 0.42 ±0.26b | ||||
| Feed consumption, kg | ||||||||
| Pre-farrowing | 19.62 ± 1.84a | 18.61 ± 1.96 | 16.85 ± 1.84b | 20.02 ± 1.78a | ||||
| Week 1 | 16.46 ± 2.45 | 15.05 ± 2.54 | 17.34 ± 2.43 | 16.25 ± 2.38 | ||||
| Week 2 | 27.52 ± 2.54a | 24.14 ± 2.64b | 25.90 ± 2.56 | 25.95 ± 2.50 | ||||
| Week 3 | 31.44 ± 2.57 | 29.19 ± 2.67 | 30.58 ± 2.60 | 28.93 ± 2.49 | ||||
| Week 4 | 33.75 ± 2.51 | 33.29 ± 2.55 | 34.31 ± 2.48 | 31.49 ± 2.38 | ||||
| ab Means in a row with different superscripts differ (P < 0.10). | ||||||||
Figure 1. Average sow backfat during lactation.
Figure 2. Daily sow weight change during lactation.
Feed consumption results (Table 2, Figure 3) also were difficult to
interpret, because only minor differences were detected that were not
consistent across weeks. Pre-farrowing, sows fed the 0 and 9% added fat
diets had greater consumption than those fed the 6% added fat diet.
During week 2 of lactation, sows fed the 0% added fat diet consumed
significantly more feed than those fed the 3% added fat diet.
Figure 3. Weekly sow feed consumption during lactation.
The number of pigs born alive (Table 3, Figure 4) was not affected by fat level. The number of mummified fetuses was greater for sows fed the 9% added fat diet compared to those fed the 0% added fat ration. Litter size weaned was greatest for sows fed the 0% added fat diet, which was an unexpected result of this study. Other studies have indicated that pig survival has increased as a result of supplemental fat in lactation diets.
Figure 4. Weekly pig weights of sows fed varying fat
levels during lactation.
Average pig weights (Table 3) were greater for sows fed added fat diets; however, the only significant differences occurred between pigs nursing sows which were fed the 3% added fat diet compared to those nursing sows fed the control diet during weeks 3 and 4 of lactation.
In general, the documented effects of feeding supplemental fat in late gestation and lactation include 1) increased fat concentration in colostrum and milk; 2) increased survival rates of piglets if the herd survival rate is below 80%; 3) little or no effect of dietary fat on litter size at birth; and 4) increased average pig weaning weight if the diet contains at least 8% fat. Results of this experiment were not clear in terms of the general trends related to feeding supplemental fat in lactation diets.
| Table 3. Least squares means for litter traits. | ||||||||
| Fat level, % | ||||||||
| Trait | 0 | 3 | 6 | 9 | ||||
| Number born alive | 9.76 ± 0.73 | 9.78 ± 0.74 | 9.78 ± 0.71 | 9.52 ± 0.69 | ||||
| Number of stillborns | 1.68 ± 0.45 | 1.70 ± 0.45 | 1.64 ± 0.44 | 1.57 ± 0.42 | ||||
| Number of mummies | 0.076 ± 0.17a | 0.078 ± 0.17 | 0.144 ± 0.16 | 0.273 ± 0.16b | ||||
| Number weaned, 28 days | 8.66 ± 0.71a | 8.00 ± 0.72 | 8.11 ± 0.69 | 7.80 ± 0.67b | ||||
| Average pig birth weight, kg | 1.34 ± 0.08 | 1.39 ± 0.07 | 1.34 ± 0.07 | 1.32 ± 0.06 | ||||
| Average pig weight week 1, kg | 2.59 ± 0.16 | 2.72 ± 0.16 | 2.70 ± 0.15 | 2.69 ± 0.15 | ||||
| Average pig weight week 2, kg | 4.13 ± 0.21 | 4.31 ± 0.22 | 4.31 ± 0.21 | 4.27 ± 0.20 | ||||
| Average pig weight week 3, kg | 5.45 ± 0.29a | 5.80 ± 0.29b | 5.60 ±0.28 | 5.72 ±0.28 | ||||
| Average pig weight week 4, kg | 6.98 ± 0.38a | 7.48 ± 0.38b | 7.26 ± 0.36 | 7.39 ± 0.35 | ||||
| ab Means in a row with different superscripts differ (P < 0.10). | ||||||||
The authors gratefully acknowledge the work of David Owens and the other OARDC Western Branch employees.