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Calcium, phosphorus needs of sows in stalls versus groups

DETERMINING calcium and phosphorus requirements of swine has been a subject of research for many years.

By JOHN GOIHL*

*John H. Goihl is president of Agri-Nutrition Services Inc., Shakopee, Minn.

DETERMINING calcium and phosphorus requirements of swine has been a subject of research for many years.

Researchers agree that the calcium and phosphorus requirement for bone mineralization and strength is higher than the requirement for growth and reproductive performance.

Research studies have shown inconclusive results of varying the calcium and phosphorus levels in sow diets. Some studies have shown no improvement in reproductive performance or longevity when sows were fed increased levels of calcium and phosphorus, whereas other studies have shown a greater incidence of lameness in sows with low calcium and phosphorus intake.

Calcium and phosphorus play a major role in the growth, development and maintenance of the skeletal system, and the majority of calcium and phosphorus is stored in the bone.

The new standards for housing sows in pens instead of individual stalls has researchers questioning if the current calcium and phosphorus recommendations for gestating sows in stalls is adequate for gestating sows housed in pens.

Sows are housed in individual stalls to control feed intake and aggression, which limits movement and mobility, but it also has been shown to reduce bone strength. Laying hen research has demonstrated that hens with more opportunity for movement had a greater capacity to mobilize bone calcium reserves for eggshell formation, suggesting a need for additional dietary calcium.

Swine researchers F.P.Y. Tan, S.A. Kontulainen and A.D. Beaulieu at the University of Saskatchewan and Prairie Swine Centre conducted a study to determine if the recommended levels of dietary calcium and phosphorus for sows in stalls are adequate for sows housed in groups with increased mobility.

The study consisted of 180 sows of multiple parities that were assigned to one of six treatments: three dietary levels and two housing systems. The two housing systems were either gestation stalls or gestation pens.

The sows had been housed in free-access stalls prior to the initiation of the experiment. The trial started when sows were moved from the breeding stalls to the gestation barn, which occurred approximately 28 days into gestation. Each treatment group had a balance of parities. The trial ended when piglets were weaned at an average of 26 days after farrowing. Each week, 16 sows were mated and remained in breeding stalls until moved to a gestation barn.

The gestation pens consisted of an alley with slatted floors between two rows of 16 free-access stalls and a solid-floor loading area at one end. Feed and water were available in each stall, plus there was a nipple drinker in the loafing area. Sows were moved into farrowing crates one week before anticipated farrowing. Cross-fostering was done within the first 24 hours and within dietary treatment.

The three dietary treatments included: (1) low — 15% lower than the control; (2) a control diet based on National Research Council and National Swine Nutrition Guide recommendations, and (3) high — 15% higher than the control. The formulated calcium and phosphorus levels of the gestation and lactation diets are summarized in Table 1.

The diets were barley/wheat/soybean meal fortified.

Gestation feeding began when the sows were moved to the gestation room. Sows were fed 2.3 kg per day until two weeks prior to farrowing, when the amount was increased to 3.0 kg per day.

Sows had ad libitum access to the treatment diets during lactation, except for the first three days post-farrowing, when daily feed intake was limited to 0.5 kg on day 1 and increased to 4.0 kg on day 3.

Sows were weighed prior to entry into the gestation room, upon entry to farrowing and 26 days after farrowing. The number of piglets (i.e., born alive, stillbirths and mummies) and birth and weaning weights were all recorded.

Video recordings of sow movement were collected for 13 hours on weeks 1 and 5. On week 5, sow posture and stepping behavior were recorded. Fecal samples were collected from 10 sows per treatment on day 60 of gestation and day 14 of lactation for three consecutive days.

Blood samples were collected on days 1 and 100 of gestation and days 14 and 26 of lactation. Milk samples were collected on days 12 and 25 of lactation.

Table 2 summarizes the effects of treatment and housing on sow and litter performance.

Table 3 summarizes the effect of parity on sow weight change and lactation feed intake.

The researchers noted that a total of 18 sows were removed from the trial for various reasons not related to the treatments.

The researchers provided the following interpretations of the results:

* There was no effect of treatment or housing on the change in bodyweight of sows from day 28 of gestation to day 107 of gestation.

* The average daily feed intake of sows during lactation was not affected by treatment.

* Group-housed sows produced one additional live-born piglet and had heavier piglets than sows housed in stalls.

* On day 100 of gestation, sows housed in stalls and fed treatment 3 (high calcium and phosphorus levels) had the smallest change in serum phosphorus levels. The greatest decline in serum phosphorus levels was observed in group-housed sows fed treatment 1 (low calcium and phosphorus levels).

* Younger sows generally had greater serum total calcium and phosphorus concentrations at all time points than older sows.

* Group-housed sows fed treatment 3 produced milk with the greatest amount of calcium.

* Stall-housed younger sows in mid-lactation produced milk with the lowest calcium levels (0.15%), whereas milk produced by sows in the other treatment groups had similar calcium levels (0.16%).

* The amount of calcium excreted in the feces increased as the level of calcium increased.

* There were no effects of dietary calcium and phosphorus or housing on the number of steps taken, the amount of time spent standing or the duration that each sow spent in different postures at week 5 of gestation.

Results from previous studies indicated that dietary calcium and phosphorus levels or housing did not affect sow bodyweight or average daily feed intake during gestation or subsequent sow reproductive performance.

Also, previous studies have shown that stall housing resulted in decreased muscle weight and bone strength compared to group-housed sows, indicating that movement or exercise may be important for bone and muscle development.

 

The Bottom Line

The results of this study imply that the level of dietary calcium and phosphorus recommended by the National Research Council is adequate for sows of today's genetics, whether housed in stalls or groups.

 

Reference

J. Anim. Sci. Vol. 94, No. 10.

 

1. Formulated calcium and phosphorus levels of gestation and lactation diets used in the experiment

 

-Gestation-

-Lactation-

Treatment

1

2

3

1

2

3

Standard ileal digestible lysine, %

0.45

0.45

0.45

0.80

0.80

0.80

Calcium, %

0.60

0.70

0.80

0.61

0.71

0.82

Available phosphorus, %

0.27

0.32

0.37

0.30

0.36

0.42

 

2. Effects of treatment and housing on sow and litter performance

 

-Treatment-

-Housing-

 

1

2

3

Stall

Group

Number of sows

51

54

57

81

81

Piglets born live

14.2

14.3

14.7

13.9

14.9

Total litter size

15.2

15.6

16.1

15.2

16.1

Birth weight, kg

1.56

1.51

1.49

1.49

1.55

Weaning weight, kg

6.67

6.58

6.72

6.59

9.73

Average daily gain of litter, kg

0.23

0.23

0.23

0.23

0.23

 

3. Effect of parity on sow weight changes and lactation feed intakes

 

Gilts and

Sows at

Criteria

parity 1 sows

parity 2 or more

Number of sows

80

82

Sow bodyweight, kg

 Day 28 of gestation

201.0

261.3

 Day 107 of gestation

241.4

280.1

 Weaning at day 26 of lactation

217.9

266.9

Sow bodyweight change, kg

 Days 28-107

38.7

20.3

 Day 28 to weaning

14.1

8.0

Average daily feed intake, kg

6.4

7.4

 

Volume:88 Issue:12

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