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Organic Agriculture

, Volume 7, Issue 3, pp 267–279 | Cite as

Effect of six 100 % organic feeding strategies differing in external input demand on animal performance and production costs of piglets before and after weaning

  • L. Baldinger
  • R. Bussemas
  • K. Höinghaus
  • A. Renger
  • F. Weißmann
Article

Abstract

Organic agriculture aims at incorporating livestock as part of the farm ecosystem and therefore strives to minimize the use of external inputs. Minimizing external inputs is especially challenging in feeding of piglets, because the high-quality protein feeds needed to meet their demand are usually not available on farm or at least not in sufficient quantity. In an experiment, 1509 piglets were allocated to six different feeding strategies before and shortly after weaning at 49 days. Each feeding strategy was a combination of one out of three 100 % organic concentrates differing in external input demand (bought in protein-rich feeds) and one out of two forages (grass-clover silage and straw). The type of forage had no influence on piglets’ performance before and after weaning, but the type of concentrate had: the lowest quality concentrate with the lowest amount of external inputs led to the lowest daily weight gain, while the medium- and high-external input demand concentrates did not differ. The higher the proportion of external inputs, the better the concentrate conversion ratio but also the higher the price. Despite slower growth, the time and amount of concentrate needed to raise a 20-kg piglet were not influenced by dietary treatment and neither was piglet health. Therefore, the use of the cheapest concentrate with the lowest proportion of external inputs can be recommended for piglets with a 49-day suckling period and under generally good management conditions.

Keywords

Organic farming Nutrition Piglet External input 

Introduction

Organic agriculture understands the farm as an ecosystem defined by nutrient cycles incorporating the soil, plant production, livestock, and various nutrient imports and exports. Ideally, production maximizes the use of on-farm resources and minimizes imports (see IFOAM’s Principle of Ecology, Luttikholt 2007). Livestock plays an important role by using feed resources unsuitable or not needed for human consumption to produce food and also manure for plant production, but feed resources suitable for human consumption are usually used as well. However, meeting the demands of highly productive farm animals can push the limits of on-farm feed resources. This is especially true for piglets before and immediately after weaning, who require highly digestible diets rich in high-quality protein (Zollitsch 2007). Dietary protein supply has been shown to influence piglets’ health after weaning, with both too low (malnutrition) and too high (diarrhea) protein supply having negative consequences (Werner and Sundrum 2008, Heo et al. 2013). Offering piglets the best possible start in life is a self-evident goal in the service of animal welfare, but potential long-term benefits of stimulating growth before and directly after weaning on the performance during fattening have also been discussed (Williams 2003). So far, scientific reports about organic diets for piglets before and after weaning have not focused on the necessary amount of bought-in feed (hereafter named “external inputs”). The available literature about 100 % organic diets for piglets can be summarized insofar, as the high-quality protein feeds commonly used include press cakes (mostly from soybean, sunflower, and rapeseed), treated grain legumes (e.g., toasted faba beans), and dried milk products (mostly skimmed milk powder) (e.g., Lindermayer and Probstmeier 2003; Stalljohann 2006; Baldinger et al. 2014; Witten et al. 2014). Formulating a balanced organic diet for piglets is nearly impossible without these components, of which most are not commonly available on an average central European pig farm, at least not in sufficient quantities. A recent report on protein availability and demand in the main pig-producing countries in Europe estimated a self-sufficiency rate for crude protein of 56%, meaning that almost half of the protein has to be imported (Früh et al. 2015). In contrast to the difficulty of minimizing external inputs in organic feeding of piglets, feeding growing-finishing pigs with mainly farm-based components has been found to be relatively easy. The supplementation of small percentages of high-quality external components such as potato protein or whey powder ensured the best performance, but also without these, acceptable performance could be achieved (Sundrum et al. 2000; Partanen et al. 2006).

In order to provide information on the effect of diets differing in external input demand on piglets’ performance, a trial comparing different feeding strategies was conducted. Each feeding strategy was a combination of one out of three concentrates and one out of two forages. The concentrates differed in their external input demand, resulting in different energy and nutrient compositions. The forages were either grass clover silage or straw. In order to avoid confounding effects of differently long suckling periods, all three concentrates were fed to piglets weaned after 49 days. The diets were fed to a total of 1509 piglets before and after weaning, up to an age of 63 days.

The aims of the experiment were to examine the effect of three different concentrates differing in external input demand, of two forages, and the interaction between forage and concentrate on the performance of piglets before and after weaning. Apart from feed allowance and body weight gain, losses and medical treatments were documented and serum haptoglobin was analyzed in order to detect potential effects of dietary treatment on the piglets’ health.

Animals, materials, and methods

The feeding trial was conducted between March 2012 and August 2014 at the experimental station of Thuenen Institute of Organic Farming in Trenthorst, Germany. Animal husbandry followed the rules of EU Directive EC 834/2007 (The Council of the European Union 2007) and the production guidelines of the German organic farming association (Bioland 2014), and all feeds were of 100 % organic origin.

Animals

The breeding sows in the herd were crosses of Landrace x Large White, which were inseminated with either Piétrain or Danish Duroc. From 1 week ante partum until 2 week post partum, the sows were kept in individual, straw-bedded farrowing pens of 7.8-m2 indoor area equipped with a heated creep area, plus a 5.9-m2 outdoor area. Two weeks post partum, sows and piglets were combined into groups of 3–6 sows plus litters and thereafter housed in a group suckling housing system, offering the same space allowance per sow and including a creep area for the piglets as well. A previous study by Bussemas and Weißmann (2015) found no effect of group size on piglets’ performance; therefore, group size was not constant. Iron injections were administered to the piglets on day 3 and 14, and castration of 5–10-day old male piglets was performed under anesthesia and pain relieving drugs. At weaning (49 ± 5 days), sows were removed from the group housing system, and 4 days later, the piglets were moved to their rearing pens. The experiment was conducted in accordance with EU Directive 2010/63/EU (The European Parliament and the Council of the European Union 2010) for animal experiments. Taking blood samples of the piglets was the only invasive procedure in the service of the experiment.

Feeding regimen

The experimental unit for offering an experimental diet was not a single litter, but the group of litters combined in the group suckling housing system. Each experimental diet consisted of a combination of one out of three experimental concentrates and one out of two experimental forages. The experimental forages were offered as soon as the sow moved into the individual farrowing pen, about 1 week ante partum. Feeding of the experimental concentrates started after the move to the group housing system, when piglets were on average 14 days old. The piglets received the same concentrate before and after weaning, to avoid digestive problems associated with a change in diet after weaning. The experimental concentrates differed in their demand for feed components usually not produced on an average organic pig farm in central Europe but bought in instead (“external inputs”).

Concentrate HID (high-external input-demand) was a commercial compound feed formulated according to the current feeding recommendations of Lindermayer et al. (2011) for piglets weighing 10–20 kg (13 MJ ME and 180-g crude protein kg−1 feed), which are based on a suckling period of a minimum of 40 days. HID contained expensive components such as extruded faba beans, toasted soybeans, and skimmed milk powder, summed up to 72 % external inputs. Concentrate MID (medium-external input-demand) represented using mainly home-grown feeds supplemented with bought in components. For MID, the highest quality protein-rich feeds available on organic pig farms in Northern Germany, namely peas and blue lupins, were used in combination with 22.5 % bought in feeds, mostly soybean cake and whey powder. Concentrate LID (low-external input demand) was formulated according to the recommendation of Lindermayer et al. (2011) for lactating sows (12.8 MJ ME and 175-g crude protein kg−1 feed) and therefore represented the possibility of feeding the same feed to the sow and the piglets during the suckling period. Only 13 % external inputs were needed for LID, which was to outcome of a pre-trial on minimizing external inputs in feed for suckling piglets, which was found to achieve satisfactory results under a longer suckling period of 49 days (Weissmann and Bussemas 2010, unpublished data). Both MID and LID did not meet Lindermayer et al. (2011) recommendations for piglets weighing 10–20 kg, but the difference varied: LID and MID were 0.4 and 0.2 MJ ME kg−1 feed lower in energy than recommended, respectively. The crude protein content of LID was 27 g kg−1 feed less than recommended in LID, while the difference in MID was only 2 g kg−1 feed. The dry and pelleted concentrates were offered in one feeder per pen, in amounts adjusted to the piglets’ appetite but resulting in very little feed refusals (“semi-ad libitum”). The sows were fed restricted amounts of concentrate LID, depending on litter size and body condition score (BCS), with a maximum of 8-kg feed day−1.

The two forages offered to the piglets (and the sows) were grass-clover silage (Silage) and straw (Straw). Both forages were fed ad libitum and were offered twice a day in racks in the outdoor area. The provision of straw complies with the organic regulation to provide forage to all farm animals (The Council of the European Union 2007) but does not supply noteworthy amounts of energy and nutrients. Grass or grass-clover silage, on the other hand, has a much higher nutritive value and inclusion rates of up to 19 % (Carlson et al. 1999; Bikker et al. 2014) in diets for fattening pigs have been reported. It was therefore hypothesized that grass-clover silage could supply some additional nutrients to the young piglets and soften the potential nutrient undersupply caused by feeding a concentrate with very little external inputs. The composition and nutrient contents of the experimental concentrates and forages (not subjected to statistical analysis) are summarized in Table 1.
Table 1

Composition and nutrient contents of experimental diets, g kg−1 DM unless stated otherwise. Concentrates: HID (high-), MID (medium-), LID (low-external-input demand). Forages: silage (grass-clover silage), straw (barley straw)

Dietary components and nutrients

Concentrates

  

Forages

  

HID

MID

LID

SEM

P value

Silage

Straw

SEM

P value

N = 4

N = 4

N = 4

 

N = 4

N = 4

 

Triticale

 

275

300

    

Winter barley

280

200

270

    

Peas

 

200

200

    

Blue lupins

 

100

 

    

Faba beans*

222

 

100

    

Soybeans, toasted

174

  

    

Soybean cake

 

143

48

    

Rapeseed cake

  

50

    

Whey powder

 

50

 

    

Skimmed milk powder

60

  

    

Wheat flakes

220

  

    

Sunflower oil

10

5

5

    

Mineral mix

34

27

27

    

DM**

885b

877ab

863a

3.8

0.011

263

985

25.3

<0.001

Crude protein

205b

201b

177a

14.8

0.008

156

39

8.9

<0.001

Lysine

11.9b

11.3ab

10.0a

1.04

0.013

n.a.

n.a.

Methionine

3.0b

2.6ab

2.4a

0.40

0.024

n.a.

n.a.

Crude fiber

46.3

51.8

58.5

4.66

0.251

222

453

18.6

<0.001

ME, MJ

15.4b

14.6a

14.6a

0.43

0.008

n.a.

n.a.

g lysine MJ−1 ME

0.78

0.77

0.69

0.024

0.052

n.a.

n.a.

Price, €

1.28

0.66

0.54

    

External inputs, %

72.0

22.5

13.0

    

Means within a row with different superscripts differ (P < 0.05)

ME metabolizable energy, calculated according to GfE18; n.a. not analyzed; − not applicable;

*In HID, faba beans were extruded

**g kg−1 fresh weight

Data collection and analytical procedures

Because of the group suckling system, concentrate allowance was documented as the sum of feed offered to the total group of piglets from 3 to 6 l. Very little, if any, feed refusals were recorded because of semi-ad libitum feeding. Forage allowance was documented at the start of the experiment but was stopped soon because of the following observations: Especially during the suckling period, piglets played with Silage more than they consumed it, and Straw offered in the rack was neither played with nor consumed, therefore documenting the forage allowance did not provide any information. Piglets were weighed individually once a week throughout the whole experimental period. Daily weight gain was calculated from individual body weight. Concentrate conversion ratio was defined as kg concentrate (as fed) divided by total weight gain of group. Despite the fact that feed costs fluctuate heavily throughout the year, an economic comparison of the dietary treatments was attempted. However, only the concentrate cost and not the cost for forage was included, because forage costs differ even more between farms. The concentrate prices stated in Table 1 represent the average prices observed in Northern Germany between March 2012 and August 2014 and were calculated as follows: For HID, which was a commercial compound feed, the market price was used. The feed costs of MID and LID, which were produced on the experimental farm, were calculated from the market prices of the bought-in components and the price of the on-farm components for which they could have been sold at the time of the harvest. Concentrate cost kg−1 weight gain was calculated by multiplying the concentrate conversion ratio with feed costs. In order to eliminate the effect of differing body weights of piglets at the end of the experimental period, the amount of concentrate and the concentrate costs were calculated for a standardized piglet of 20 kg.

Blood samples of piglets for analysis of serum haptoglobin were taken 6 days after weaning (age 55 days) by puncturing the vena jugularis externa, using vacutainer tubes. Serum haptoglobin was photometrically determined at LMU Munich, Department for Animal Welfare, Ethology, Animal Hygiene and Animal Husbandry (Munich, Germany), using a commercial kit (BioRépair GmbH, Sinsheim, Germany). All medical treatments administered to the piglets were routinely documented. Every 6 months, one sample of each experimental concentrate was taken for analysis of nutrients, resulting in a total of four samples of each diet. The samples were sent to a commercial laboratory for analysis of nutrients according to VDLUFA (2007). The body condition score of the sows on a scale from 1 to 5 (MAFF 1998) was assessed directly after farrowing and again after weaning.

Description of the dataset

Throughout the experiment, a total of 35 breeding sows produced a total of 174 litters. The length of the suckling period is an important influence on piglet performance and health; therefore, very short and very long suckling periods could potentially skew the dataset. The targeted length of the suckling period was 49 ± 5 days, and 30 l were excluded from the original dataset because their suckling period was shorter or longer. The final dataset included 144 l with 1509 piglets (at age 14 days). Most of the breeding sows contributed more than 1 l to the dataset, with an average of 2.6 ± 1.3 l per sow. Averaged over the whole experimental period, sows were in their 5.1 ± 3.4th parity, with 16 first parities and one 16th parity included in the dataset. Table 2 shows the number of litters and piglets in the database, and means + standard deviation for piglets’ age, body weight, concentrate allowance, and the sows’ body condition score (BCS).
Table 2

Number of litters and piglets included in the database and description (mean + standard deviation) of piglets’ age, body weight, and concentrate allowance and parity and body condition score (BCS) of the sows

 

Concentrates

 

HID

MID

LID

 

Silage

Straw

Silage

Straw

Silage

Straw

Number of…

 Litters

24

24

24

24

24

24

 Piglets at the start of the exp.

259

261

259

246

233

251

 Piglets at weaning

255

255

252

243

224

251

 Piglets at the end of the exp.

255

255

251

243

224

251

Age of piglets, days

 At the start of the experiment

16 + 2.2

14 + 2.2

17 + 3.3

16 + 1.9

14 + 1.4

17 + 2.9

 At weaning

50 + 1.6

49 + 1.6

49 + 1.3

48 + 1.6

49 + 2.2

49 + 1.8

 At the end of the experiment

62 + 1.8

62 + 1.7

63 + 1.5

61 + 3.9

62 + 2.4

62 + 2.2

Body weight of piglets, kg

 Day 14

4.4 + 1.1

4.4 + 1.1

4.5 + 1.1

4.4 + 1.1

4.5 + 1.0

4.4 + 1.1

 Day 49

14.4 + 3.2

15.7 + 3.5

16.5 + 3.6

14.5 + 3.3

14.8 + 3.8

15.6 + 3.2

 Day 63

19.9 + 4.6

22.2 + 4.9

22.3 + 4.9

19.1 + 4.6

19.0 + 4.7

20.9 + 4.2

Concentrate allowance, g DM day−1

 Suckling period

51 + 49

71 + 83

71 + 73

64 + 75

86 + 97

94 + 102

 Rearing period

497 + 229

624 + 243

629 + 217

523 + 167

562 + 197

644 + 178

 Total period

246 + 271

308 + 323

310 + 316

261 + 259

291 + 279

330 + 307

 Parity of sows

5.1 + 3.4

4.6 + 3.4

4.8 + 3.5

5.0 + 3.4

5.6 + 3.4

5.4 + 3.4

BCS of sows

 Immediately post partum

4.1 + 0.6

4.1 + 0.6

4.0 + 0.6

4.0 + 0.6

4.1 + 0.6

4.1 + 0.6

 At weaning

3.8 + 0.7

3.8 + 0.7

3.8 + 0.7

3.8 + 0.7

3.9 + 0.7

3.8 + 0.7

Statistical analysis

All statistical analysis was conducted using program package SAS 9.4 (SAS 2013). When P < 0.05, differences were interpreted as significant, and following Lowry (1992), the interaction concentrate*forage was only studied when it had a significant effect.

The nutrient contents of the feeds were analyzed using proc GLM, with a model including only the fixed effect of feed. Proc GLIMMIX was used for analyzing the frequency of treatments and losses, with a model including the fixed effects of concentrate (C: HID, MID, LID) and forage (F: Silage, Straw), the random effect of litter and the interaction concentrate*forage. All other parameters were analyzed with proc MIXED, using the covariance structure Variance Components. The statistical models included the random effects of litter and piglet, the fixed effects of Concentrate, Forage, Day of Life and Season of Birth, the covariate birth weight (difference between birth weight and average birth weight of the treatment group), and the interaction concentrate*forage. Because the basis of measurement (individual piglet versus group of litters combined in the group suckling and rearing system) and the frequency of measurement (repeatedly versus only once) differed, the models for the parameters differed slightly and were as follows:

Concentrate allowance

$$ \mathrm{Y}=\upmu +\mathrm{C}+\mathrm{F}+\mathrm{C}*\mathrm{F}+\mathrm{Day}\ \mathrm{of}\ \mathrm{Life}+\mathrm{Season}\ \mathrm{of}\ \mathrm{Birth}+\mathrm{birth}\ \mathrm{weight}+\mathrm{Litter}+\upvarepsilon $$

Body weight and daily weight gain

$$ \mathrm{Y}=\upmu +\mathrm{C}+\mathrm{F}+\mathrm{C}*\mathrm{F}+\mathrm{Day}\ \mathrm{of}\ \mathrm{Life}+\mathrm{Season}\ \mathrm{of}\ \mathrm{Birth}+\mathrm{birth}\ \mathrm{weight}+\mathrm{Litter}+\mathrm{Piglet}+\upvarepsilon $$

Blood haptoglobin

$$ \mathrm{Y}=\upmu +\mathrm{C}+\mathrm{F}+\mathrm{C}*\mathrm{F}+\mathrm{Litter}+\mathrm{Piglet}+\upvarepsilon $$

Production efficiency and feed costs

$$ \mathrm{Y}=\upmu +\mathrm{C}+\mathrm{F}+\mathrm{C}*\mathrm{F}+\mathrm{Sow}+\upvarepsilon $$

Parameters of production efficiency and feed costs were only calculated once for each litter; therefore, the random effect of sow was used instead of the random effect of litter.

Table 1 shows least square estimates of the nutrient contents of the feeds and P values and standard errors of the mean (SEM) for the effect of feed. No significant effect of the type of forage on parameters of feed allowance, performance, production efficiency, and feed cost could be found. Therefore, the least square estimates and SEMs shown in Tables 3 and 4 are those of the effect of concentrate. P values are given for the effects of concentrate, forage, and their interaction, and are printed bold when a value below 0.05 indicates a significant effect. Whenever the dataset was not balanced, SEM is given as a range. Table 5 shows least square estimates of the interaction concentrate*forage for serum haptoglobin and frequencies for treatments and losses.
Table 3

Feed allowance and performance of piglets fed 100 % organic diets differing in external input demand before and after weaning. Concentrates, C: HID (high-), MID (medium-), LID (low-external-input demand). Forages, F: silage (grass-clover silage), straw (barley straw). The table shows least square estimates for the effect of concentrate. Animal numbers (N) refer to the start of the experiment

 

Concentrates

SEM

P values

 

HID

MID

LID

 

C

F

C × F

 

N = 520

N = 505

N = 484

    

Concentrate allowance, g day−1

 Suckling period

63

82

77

6.8–8.4

0.188

0.883

0.641

 Rearing period

595b

641b

522a

18.5–22.7

0.001

0.951

0.057

 Total period

268ab

298b

245a

10.9–13.5

0.027

0.926

0.454

Age of concentrate allowance

  > 100g, days

34b

33ab

32a

0.58–0.59

0.024

0.504

0.747

Body weight, kg*

 Day 14

4.9

5.0

4.6

0.26–0.32

0.001

0.453

0.219

 Day 49

15.2

15.6

15.6

 Day 63

22.2

21.8

20.9

Daily weight gain, g

 Suckling period

299a

362b

295a

9.7–11.4

<0.001

0.314

0.245

 Rearing period

450b

397b

317a

18.4–21.3

<0.001

0.539

0.322

 Total period

336b

368b

291a

9.8–11.7

<0.001

0.400

0.109

Means within a row with different superscripts differ (P < 0.05)

Suckling period day 14–49, rearing period day 49–63, total period days 14–63

*P values and SEM refer to the total period; least square estimates for individual days are given for further illustration

Table 4

Animal health and losses of piglets fed 100 % organic diets differing in external input demand before and after weaning. Concentrates, C: HID (high-), MID (medium-), LID (low-external-input demand). Forages, F: silage (grass-clover silage), straw (barley straw). The table shows least square estimates for the interaction concentrate*forage for blood haptoglobin and frequencies for treatments and losses

 

Concentrates

SEM

P values

 

HID

MID

LID

 

C

F

C × F

 

Silage

Straw

Silage

Straw

Silage

Straw

    

Blood haptoglobin on day 55, mg ml−1

2.7c

2.8c

1.9ab

2.2bc

2.3bc

1.7a

1.58–2.23

<0.001

0.257

0.036

Treatments

14

6

10

3

21

11

0.162

0.050

0.797

Losses

4

6

8

3

9

7

0.187

0.049

0.760

Means within a row with different superscripts differ (P < 0.05)

− not applicable

Table 5

Production efficiency and feed cost of 100 % organic diets differing in external input demand fed to piglets before and after weaning. Concentrates, C: HID (high-), MID (medium-), LID (low-external-input demand). Forages, F: silage (grass-clover silage), straw (barley straw). The table shows least square estimates for the effect of concentrate

 

Concentrates

SEM

P values

 

HID

MID

LID

 

C

F

C × F

 

N = 48

N = 48

N = 48

    

Concentrate conversion ratio*

 Suckling period

0.40a

0.47a

0.59b

0.024

<0.001

0.275

0.728

 Rearing period

1.90a

2.23b

2.36b

0.077

<0.001

0.622

0.234

 Total period

0.91a

1.00b

1.11b

0.028

<0.001

0.416

0.340

Concentrate cost kg−1 weight gain, €

 Suckling period

0.51b

0.30a

0.32a

0.020

<0.001

0.154

0.404

 Rearing period

2.44b

1.47a

1.28a

0.061

<0.001

0.966

0.383

 Total period

1.17b

0.66a

0.60a

0.024

<0.001

0.175

0.105

Requirements for a 20-kg piglet

 Total period, days

61

62

63

1.0

0.268

0.522

0.100

 Concentrate, kg DM

14.3

15.2

15.4

0.55

0.306

0.274

0.077

 Concentrate cost, €

20.7c

11.6b

9.8a

0.64

<0.001

0.289

0.144

Means within a row with different superscripts differ (P < 0.05)

Suckling period day 14–49; rearing period day 49–63; total period days 14–63

*kg concentrate (as fed) kg−1 weight gain

Results

Feed composition

The experimental concentrates differed in almost all nutrient contents (see Table 1). Concentrate HID had the highest crude protein, lysine, and methionine concentration, followed by MID, while the concentrations were lowest in LID. The energy value of HID was highest as well, while MID and LID did not differ in that respect. Setting the concentrations in HID as 100 %, the crude protein content of MID was 98 % and that of LID was 86 % of HID. Energy concentration was 95 % of HID in both MID and LID, while concentrate cost was 52 % of HID for MID and 42 % of HID for LID.

The forages differed significantly in their crude protein and crude fiber contents, with crude protein being four times higher and crude fiber being less than half in Silage as compared to Straw.

Feed allowance, performance, and health of piglets

None of the performance parameters shown in Table 3 were influenced by the type of forage, but almost all were significantly affected by the type of concentrate. Concentrate allowance over the total period was 270 g day−1 when Silage was fed and 271 g day−1 when Straw was fed (not shown in Table 3). The age at which concentrate allowance reached 100 g day−1 was significantly affected by the type of concentrate, but the difference between HID and MID, and between MID and LID, was only a single day, respectively. Averaged over the suckling period, concentrate allowance was considerably lower than 100 g day−1 and was not affected by dietary treatment. During the rearing period, concentrate allowance was about eight times higher than during the suckling period, and feeding LID resulted in a significantly lower concentrate allowance than HID and MID, which did not differ. Calculated for the total period, concentrate allowance was 22 % higher when MID was fed as compared to LID, while HID was between the two.

The type of concentrate significantly affected the body weight and daily weight gain of piglets: Those fed LID had the lowest body weight at the end of the experiment as well as a significantly lower daily weight gain over the total period. Piglets fed HID had slightly lower body weights at weaning than those fed MID and LID but were heaviest at the end of the experiment. Accordingly, their daily weight gain was highest during the rearing phase but did not differ significantly from MID. Not depicted in Table 3 are the least square estimates for the effect of forage on daily weight gain, which were 337 g for Silage and 327 g for Straw, when calculated over the total period.

The only significant effect of dietary treatment on animal health and losses was an interaction between concentrate and forage for serum haptoglobin measured on day 55 (Table 4). The highest concentration was recorded for piglets fed HID and Silage and was 64 % higher than the concentration measured in serum of piglets fed LID and Straw. Both the frequency of medical treatments of individual piglets and the number of piglets lost during the experimental period were not affected by dietary treatment. Total losses amounted to only 2.5 %, and medical treatment was necessary for 4.3 % of the piglets.

Production efficiency and feed costs

Effects of dietary treatment on parameters of production efficiency and feed costs are summarized in Table 5. Both during the rearing and the total period, concentrate HID resulted in the significantly lowest concentrate conversion ratio but the significantly highest concentrate cost kg−1 weight gain. Concentrates MID and LID did not differ. The type of forage did not affect concentrate conversion ratio and concentrate cost kg−1 weight gain, which were 1.00 and 0.79 for Silage and 1.02 and 0.83 for Straw.

Neither the time and the amount of concentrate needed to produce a 20-kg piglet was influenced by the type of concentrate, but the cost for that concentrate was highest when HID was fed. Rearing a 20-kg piglet on MID cost 56 %, and on LID, only 47 % of the costs that arose when HID was fed. Again, no effect of the type of forage was found, and the concentrate cost for a 20-kg piglet was 14.3 € when Silage was fed and 13.7 € when Straw was fed (not shown in Table 5).

Discussion

Feed composition

There is a general agreement on the fact that it is uncomplicated to provide pigs with sufficient energy when feeding 100 % organic diets (Blair 2007). This presumption is supported by both concentrate HID and MID meeting the German (Lindermayer et al. 2011) recommendations for the energy value of organic feed for piglets weighing 10–20 kg (see Table 1). Concentrate LID was formulated as feed for lactating sows; therefore, its energy density met the respective German recommendations but was 0.4 MJ ME lower than recommended for piglets. The crude protein and lysine concentration was a different matter, however: While both HID and MID reached the German and French recommendations for crude protein concentration (Germany: 180 g kg−1 feed; France: 170–190 g kg−1 feed), not even HID met the respective recommendations for lysine (Germany: 12 g kg−1 feed; France: 11–12 g kg−1 feed) (Lindermayer et al. 2011; Roinsard et al. 2014). Therefore, in our study, only heavy use of external inputs resulted in a diet close to or meeting the current recommendations for protein concentration and quality in feed for organically raised piglets. Despite a highly variable local availability of high-quality protein feeds, meeting piglets’ protein and amino acid demand is considered one of the main challenges in pig nutrition, both on conventional, locally oriented farms and on organic farms. Apart from adequately supplying animals with energy and nutrients, an important principle to consider in formulating organic diets is the aim to incorporate livestock as a part of the farm ecosystem and consequently to maximize the use of on-farm feed resources (Luttikholt 2007). Concentrate HID neglected this principle in favor of providing the best possible diet to the piglets, but MID aimed at a compromise between the piglets’ demand and the reduction of external inputs. MIDs energy value was significantly lower than in HID, but its crude protein, lysine, and methionine contents did not differ significantly. It was therefore possible to produce a diet close to the recommendations mainly using on-farm feed resources. Concentrate LID focused on minimizing both external inputs (only 13 %; see Table 1) and the workload in the farrowing section by feeding a single diet to both the lactating sows and the piglets. From the piglets’ standpoint, LID did not meet the feeding recommendations and with significantly lower crude protein, lysine, and methionine contents than HID and MID presented the risk of undersupplying piglets.

Feed allowance, performance, and health of piglets

During the suckling period, the single most important influence on the performance of piglets is the milk yield and behavior of the sow. BCS values of the sows as shown in Table 2 (not subjected to statistical analysis) were almost identical for all treatment groups, with average values of 4.1 + 0.6 directly after farrowing and 3.8 + 0.7 after weaning. Mobilization of body reserves during lactation was therefore moderate, and sows were slightly fatter than the MAFF (1998) recommendations of BCS 3.0–4.0 at farrowing and >2.5 at weaning. Combined with the fact that, according to Hansen et al. (2012), a high BCS is a favorable influence on milk persistency, it can be assumed that the effect of dietary treatment was not biased by a lack of milk or differences in milk yield. This assumption is further supported by the fact that the age at which concentrate allowance reached a noteworthy level (>100 g day−1) ranged in a narrow band from 32 to 34 days, even though the differences between dietary treatments were significant (Table 3).

It is the usual practice at the experimental station to wean piglets at 49 days instead of the minimum of 40 days required by the regulations for organic agriculture (The Council of the European Union 2007), because a longer suckling period has been shown to be beneficial to piglets’ health (Main et al. 2004; Bussemas and Weißmann 2008). Despite the longer suckling period, no effect of dietary treatment on concentrate allowance during the suckling period could be found. During the rearing period, however, concentrate allowance was significantly lower when LID was fed, while HID and MID did not differ. After weaning, feed intake of piglets is influenced by a variety of factors, among which are easy access to feed, the physical form of feed, its palatability, and the use of animal proteins (Brooks and Tsourgiannis 2003). Neither access to nor form of feed differed between the concentrates. But LID had the lowest proportion of treated soybean products and was the only concentrate not containing dried milk products. Therefore, the significantly lower concentrate allowance when LID was fed is thought to be due to its lack of animal proteins and inferior palatability compared to HID and MID. Concentrate allowance calculated over the whole experimental period was significantly highest for MID and lowest for LID as well, but due to the inclusion of the not-differing values from the suckling period, the differences between the treatments were much smaller.

In accordance with the differences found for concentrate allowance, body weight at the end of the experiment and daily weight gain during the rearing and total period were lowest when concentrate LID was fed and did not differ between HID and MID. Both parameters were highest when HID was fed, however. Daily weight gain during the suckling period was highest when MID was fed, while HID and LID did not differ. Since concentrate allowance did not differ during the suckling period, this observation cannot be explained by dietary treatment. Body weight at the start of the experiment was highest in piglets fed MID, which could be a reason for their higher daily weight gain during the suckling period. Body weight at weaning, which is an important determinant for growth during the ensuing fattening period (Wolter and Ellis 2001), was identical for piglets fed MID and LID. Therefore, it cannot be assumed that the negative effect of LID on daily weight gain during the rearing period could cause long-term disadvantages during fattening, especially since pigs have been shown to exhibit compensatory growth (Heyer and Lebret 2007; Berk and Weißmann 2012). However, since no data about the fattening performance of the piglets could be recorded, this cannot be explored further.

Despite lower concentrate allowance and daily weight gains, feeding concentrate LID did not result in inferior health of the piglets, as confirmed by the lack of treatment effect on piglet losses and frequency of medical treatments (Table 4). It should be noted that the experiment started when piglets were on average 14 days old. Because 90 % of piglet losses occur during the first 10 days of life, the very low level of losses observed in all treatment groups was to be expected (Roehe and Kalm 2000; Renger 2015).

Blood haptoglobin is an acute-phase protein and elevated levels indicate sub-clinical health problems (Petersen et al. 2004). Unfortunately, blood haptoglobin was only measured once, at age 55 days. Therefore, considering individual differences between the piglets as the cause for the observed significant interaction between concentrate and forage is impossible. However, all values were within the range given by Hiss and Sauerwein (2003) for healthy 4-week-old weaner pigs (1.5–4.3 mg ml−1); therefore, there is no evidence for a negative effect of dietary treatment on piglets’ health status.

The type of forage did not have any effect on piglets’ performance. Apparently, the observation that piglets consumed and played with Silage but ignored Straw does not imply that the consumed Silage supplied noteworthy amounts of energy and nutrients. The reason for the low attractiveness of Straw when offered in a rack might be the fact that straw was also used as bedding, both in the indoor and outdoor area. Feeding roughage to growing/finishing pigs has been found to stimulate exploratory and to reduce aggressive behavior, and the increased fiber intake stabilizes digestion and reduces the risk of indigestion (Werner and Sundrum 2008; Høøk Presto et al. 2009). For piglets after weaning, organic acids also present in silage have been shown to improve animal health and performance (Lallès et al. 2009). The lack of effect in this experiment could be related to the experimental period ending 2 weeks after weaning, which reduced the time in which positive effects could have become visible. Although no positive effects of feeding Silage have been found in this experiment, the advantages of feeding silage later in life are such that getting piglets used to it early in life seems recommendable.

Production efficiency and feed costs

The deviation of the energy and protein concentrations in the experimental concentrates from the current recommendations was smallest in HID, medium in MID, and biggest in LID. Exactly the same order was found for the concentrate conversion ratio, indicating that HID was the most efficient feed and LID the least efficient (Table 5). The concentrate conversion ratio was on the lower end of the range reported by Partanen et al. (2006) for weaned piglets (38–58 days) fed mainly organic diets but higher than the values given by Douglas et al. (2014) for weaned piglets (49–70 days) fed conventional diets. Taking into account the differing body weights at the end of the experiment, however, the amount of concentrate required to raise a piglet of 20 kg did not differ. Because of the lower daily weight gains observed in piglets fed LID, they took 2 days longer than the piglets fed HID to reach a body weight of 20 kg, but the difference was not significant. So the lower feed quality of LID did not result in a higher amount of feed or a longer period of time needed to raise a 20-kg piglet. This lack of treatment effect can be explained by the experimental period ending shortly after weaning and the good general health status of the piglets: The experimental period included 5 weeks of suckling period, but only 2 weeks of rearing period, during which the effects of dietary treatment on concentrate allowance and daily weight gain were more pronounced. Also, part of the differences observed for concentrate allowance and daily weight gain during the rearing period was related to differing body weights at the end of the experimental period, and calculation for a standardized 20-kg piglet removed that part of the difference. If the experimental period had been longer, the differences in piglet performance might have become more apparent and consequently resulted in more marked differences between the dietary treatments. Health problems around weaning are an important challenge on organic pig farms (Löser and Deerberg 2004) and dietary treatment did not affect animal health, as described above.

While the amount of concentrate and length of time needed to raise a 20-kg piglet did not differ, feeding HID led to concentrate costs twice as high as feeding LID. From an economic point of view, therefore, the use of concentrate LID is highly recommendable. Even though feed prices vary, the high-quality protein-rich components used in HID will always result in a considerable higher concentrate cost than MID and LID.

Compared to the quantity of concentrates required for the lactating sow (approx. 300 kg per suckling period), the feed demand for a single piglet (15 kg for a 20 kg piglet; see Table 5) is comparatively small. On the experimental farm, the yearly average of 20 piglets of 20 kg per sow requires approx. 1100 kg concentrates for the sow and only 300 kg concentrates for the piglets. This comparatively small amount of feed is a common argument for using commercial compound feed for piglets. However, if organic agriculture’s aim of minimizing external inputs is taken seriously, possibilities to reduce external inputs should not be ignored. If a change from 100 % bought-in piglet feed to a concentrate mainly based on on-farm resources is carried out, the higher demand for these resources might make slight changes in the cropping plan necessary.

Also, it should be noted that the conditions under which diet LID was found to be advantageous were very favorable: Animal care and management at the experimental station are excellent, the health and hygiene status of the herd is very high, and the suckling period is longer than usual. Especially, the higher weaning age positively influences piglet performance by smoothing the dietary transition from sows’ milk to solid feed. Feeding concentrate LID can therefore only be recommended in equally favorable conditions, and the concentrate should be offered as a single-phase feed to avoid indigestion after weaning caused by feed changes. For farms with a lower general health and management status, MID might be a better compromise between optimal nutrient supply and reducing external inputs.

Conclusions

The type of forage offered to piglets before and after weaning had no influence on piglets’ performance in this experiment. Nevertheless, offering grass-clover silage instead of barley straw seems recommendable in order to get piglets accustomed to roughage which has been shown to be beneficial during the fattening period later in life.

In this study, producing a 100 % organic concentrate (HID) that mostly met the current recommendations for energy and protein concentration was only possible with heavy use of external inputs, namely high-quality protein-rich feeds. But since neither the time nor the amount of concentrate needed to produce a 20-kg piglet differed between the dietary treatments, use of the cheapest concentrate with the lowest proportion of external inputs (LID, feed for lactating sows) can be recommended. It must be noted, however, that these results were obtained on an experimental station with very good animal care and management. On farms with less favorable conditions, concentrate MID, which contained mainly on-farm feed resources supplemented with moderate amounts of external inputs, might be a more sensible option.

Notes

Acknowledgments

This experiment was a part of the ICOPP project (improved contribution of local feed to support 100 % organic feed supply to pigs and poultry, www.organicresearchcentre.com/icopp) within the ERA-NET CORE Organic II program. Funding by the German Federal Ministry of Food and Agriculture within the Federal program for organic farming and other sustainable forms of agriculture (BÖLN, grant no. 2811oe021) is greatly acknowledged. Also, we would like to thank the farm staff at the experimental station for their diligent work during the experiment.

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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • L. Baldinger
    • 1
  • R. Bussemas
    • 1
  • K. Höinghaus
    • 1
  • A. Renger
    • 1
  • F. Weißmann
    • 1
  1. 1.Thuenen Institute of Organic FarmingWesterauGermany

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