Effects
of live yeast supplementation
on
weanling pig performance
E. van Heugten and K.L. Dorton
Summary
Effects
of yeast supplementation to diets with or without an antibiotic and high levels
of copper and zinc on nursery pig performance were evaluated. Yeast
supplementation appeared to work in concert with the other growth promotants
(zinc, copper, and antibiotics) used in this experiment. Supplementation of yeast to diets containing
these growth promotants improved pig growth performance resulting in pigs that
were 2 kg heavier than control pigs after the 6 week nursery period. However, yeast supplementation was not
effective in improving pig performance in diets without zinc, copper, and
antibiotic as growth promotants. Based
on these results, yeast supplementation to diets used in current commercial pig
production appears to be an effective strategy to improve pig performance.
Introduction
Probiotics, such as yeast, have
the ability to stimulate digestion and aid in maintaining microbial equilibrium
in the gut. Live yeast, such as Saccharomyces cerevisiae, contains
numerous enzymes that could be released into the intestine and aid existing
enzymes in the digestive tract in the digestion of feed. In addition, yeast contains vitamins and
other nutrients that may produce beneficial production responses (Kornegay et
al., 1995). In monogastrics, research
conducted to test the effectiveness of yeast cultures on performance is limited
and variable (Kornegay et al., 1995; Jurgens et al., 1997; Mathew et al.,
1998). Therefore, the objective of this
experiment was to test the effects of yeast supplementation at 107
colony-forming units per gram of feed (cfu/g) on nursery pig performance. In addition, the effects of yeast
supplementation in diets with or without pharmacological levels of copper,
zinc, and antibiotics were studied to determine if yeast could provide benefits
similar to growth promotants, or if it could act in concert with these
ingredients.
Materials and Methods
Ninety-six pigs were weaned at
seventeen days of age. Pigs were housed
four pigs per pen, using a total of 24 pens in one room. Each pen had slatted
floors and was equipped with a watering device and feeder, which allowed pigs
ad libitum access to water and feed.
The pigs were allotted to one of four dietary treatments based on
initial weight and litter origin. There
were six pens per treatment and a total of twenty-four pigs per treatment. Dietary treatments were: 1) Industry type
diet (containing growth promoting levels of zinc, copper, and antibiotic); 2)
Industry type diet with yeast (BIOSAF®); 3) Negative control (diet without high
levels of zinc, copper, and antibiotic); and 4) Negative control with yeast.
Pigs were housed in an environmentally controlled nursery with a forced air
ventilation system. Initial temperature in the nursery was 27oC
and was lowered 1oC weekly.
The nursery was not cleaned prior to the experiment to provide a more
challenging environment to the pigs. Pigs were fed three diet phases
(prestarter, starter 1, and starter 2) in 2-week intervals (Table 1). Pig weights and feed consumption were
measured on a weekly basis for six weeks.
Data were analyzed using the GLM
procedure of SAS (1998). The model
included block, diet type, yeast supplementation and the diet type by yeast
supplementation interaction.
Table 1: Composition of negative control diets*
|
|
Prestarter |
Starter
1 |
Starter
2 |
|
Corn |
41.20 |
52.13 |
60.09 |
|
Soybean Meal |
22.00 |
32.06 |
32.30 |
|
Poultry Fat |
4.0 |
4.0 |
4.0 |
|
Whey |
21.43 |
6.43 |
0 |
|
Plasma Protein |
2.75 |
0 |
0 |
|
Fish Meal |
6.85 |
2.5 |
0 |
|
Dicalcium Phosphate |
0.40 |
1.14 |
1.67 |
|
Limestone |
0.66 |
0.77 |
0.92 |
|
Vitamin and Minerals |
0.25 |
0.25 |
0.25 |
|
Salt |
0.10 |
0.40 |
0.50 |
|
Antibiotic1 |
0 |
0 |
0 |
|
Copper Sulfate |
0 |
0 |
0 |
|
Zinc Oxide |
0 |
0 |
0 |
|
Yeast |
0 |
0 |
0 |
|
Lysine-HCl |
0.15 |
0.15 |
0.15 |
|
DL-Methionine |
0.16 |
0.12 |
0.08 |
|
L-Threonine |
0.05 |
0.05 |
0.04 |
|
|
|
|
|
|
Calculated Composition |
|
|
|
|
Fat, % |
7.1 |
7.2 |
7.3 |
|
Protein, % |
23.2 |
22.7 |
20.8 |
|
Lysine, % |
1.60 |
1.40 |
1.25 |
|
Ca, % |
0.95 |
0.85 |
0.85 |
|
P, % |
0.75 |
0.70 |
0.70 |
|
*Yeast was added at the expense of corn at 0.3% to
the appropriate diets. Copper sulfate (0.095% to achieve 240 ppm of Cu), zinc
oxide (0.35% to achieve 2,500 ppm of Zn, for the prestarter diet only), and
antibiotic were added at the expence of corn to the industry type diets. 1Aureomycin 50 (400 g/ton of CTC) and
Denaguard 10 (35 g/ton of tiamulin) were used in the appropriate prestarter diets and
Tylan 40 Sulfa G (100 g/ton of tylosin/sulfamethazine) was used in the appropriate
Starter 1 and Starter 2 diets. |
|||
Results and Discussion
Diet analysis
confirmed within reasonable limits that the diets contained the specified
amounts of nutrients and minerals targeted.
Yeast cell counts in the feed were also measured (in starter 1 and 2
diets) to determine if the proper level of yeast was added to the diet and if
the yeast survived pelleting (Table 2).
Yeast counts were within specified limits and pelleting did not decrease
yeast counts, indicating that yeast survived pelleting.
Table
2. Live yeast counts of starter 1 and
starter 2 dietsa
|
|
Commercial
|
Negative Control
|
|||
|
Item |
- yeast |
+ yeast |
- yeast |
+ yeast |
|
|
Starter 1 |
|
|
|
|
|
|
Mash |
3.96 |
7.78 |
4.08 |
7.66 |
|
|
Pellet |
1.90 |
7.32 |
1.90 |
7.63 |
|
|
Starter 2 |
|
|
|
|
|
|
Mash |
2500 |
7.40 |
3.47 |
8.04 |
|
|
Pellet |
3.40 |
7.43 |
1.00 |
7.20 |
|
|
aExpressed
as log10(cfu/g). Yeast counts
were determined by SAF products on diets before pelleting (mash) and after
pelleting (pellet). |
|||||
As part of standard
operating procedures, several pigs were treated with antibiotics (injection)
because they appeared unthrifty and one pig was treated for a swollen
joint. Total number of days that pigs
were treated with antibiotics were 14, 3, 0, and 3 for dietary treatments 1 to
4, respectively. This included the pig
that was treated for 3 days for a swollen joint (dietary treatment 2). Analysis of the overall daily gain data
identified 4 pigs that had daily gains that were more than 2 standard
deviations below the mean daily gain of all pigs and could, therefore, be
considered outliers. All 4 pigs had
been fed the commercial type diet without supplemental yeast (diet 1). Therefore, the fact that these pigs grew
poorly appeared to be related to diet, rather than being a random
occurrence. For that reason, these pigs
were not removed from the data analysis.
There was a significant interaction (P < 0.05) between diet type and yeast supplementation in affecting body weights. Pigs fed diets that contained growth promoting levels of zinc, copper and antibiotics and were supplemented with yeast were 2.12 kg heavier (P < 0.001) at the end of the experimental period than pigs not supplemented with yeast. Supplementation of yeast to the negative control diets did not improve final weights of pigs (P > 0.80). Average daily gain for week 2 to 4 (P < 0.05), week 4 to 6 (P < 0.05), and overall (P < 0.01) was greater for pigs receiving yeast supplementation in industry type diets compared to those not receiving yeast. However, supplementation of yeast to negative control diets did not affect daily gain. The improvement in daily gain observed in pigs fed the commercial type diets with yeast was partly related to an increased feed intake in these pigs during week 2 to 4 (P < 0.01), and a tendency for improved intake for the overall experimental period (P < 0.10). Feed efficiency (gain/feed) tended to be improved in pigs fed commercial type diets with yeast compared to those not fed yeast only during week 1 (P < 0.10). Addition of zinc, copper and antibiotics to the diet resulted in an improvement in feed efficiency during week 0 to 2 (P < 0.05). Collectively, the results of this experiment suggest that the addition of growth promoting levels of zinc, copper and antibiotics improved pig growth performance and that supplementation of yeast was effective in further enhancing this response. However, yeast supplementation did not appear to improve pig growth performance when supplemented to diets without growth promoting levels of zinc, copper, and antibiotics.
Table
3. Performance of pigs fed different
diet types with or without yeasta
|
|
Commercial diet |
Negative Control |
Standard |
|
P value1 |
|
||
|
Item |
- yeast |
+ yeast |
- yeast |
+ yeast |
Error |
Diet |
Yeast |
D x Y |
|
Body Weight, kg |
|
|
|
|
|
|
|
|
|
Week 0 |
6.52 |
6.49 |
6.50 |
6.50 |
0.02 |
0.725 |
0.299 |
0.484 |
|
Week 1 |
7.13 |
7.43 |
7.34 |
7.23 |
0.12 |
0.950 |
0.438 |
0.108 |
|
Week 2 |
9.10 |
9.70 |
8.76 |
8.79 |
0.27 |
0.034 |
0.258 |
0.310 |
|
Week 3 |
11.96 |
13.43 |
11.70 |
11.78 |
0.26 |
0.002 |
0.009 |
0.018 |
|
Week 4 |
15.91 |
17.63 |
15.69 |
15.94 |
0.30 |
0.005 |
0.005 |
0.026 |
|
Week 5 |
21.36 |
22.89 |
20.44 |
20.12 |
0.25 |
0.001 |
0.030 |
0.003 |
|
Week 6 |
26.69 |
28.81 |
25.91 |
25.79 |
0.35 |
0.001 |
0.013 |
0.006 |
|
Daily gain, g/d |
|
|
|
|
|
|
|
|
|
Week 0-2 |
184 |
229 |
161 |
164 |
19 |
0.034 |
0.226 |
0.284 |
|
Week 2-4 |
487 |
567 |
495 |
510 |
12 |
0.059 |
0.001 |
0.015 |
|
Week 4-6 |
732 |
798 |
728 |
704 |
16 |
0.009 |
0.219 |
0.014 |
|
Overall |
480 |
531 |
462 |
459 |
8 |
0.001 |
0.010 |
0.006 |
|
Feed Intake, g/d |
|
|
|
|
|
|
|
|
|
Week 0-2 |
236 |
266 |
224 |
241 |
15 |
0.236 |
0.141 |
0.663 |
|
Week 2-4 |
626 |
721 |
683 |
671 |
17 |
0.871 |
0.029 |
0.007 |
|
Week 4-6 |
1143 |
1179 |
1072 |
1029 |
41 |
0.016 |
0.942 |
0.345 |
|
Overall |
660 |
722 |
654 |
647 |
18 |
0.037 |
0.143 |
0.073 |
|
Gain/Feed, g/g |
|
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