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Effect of dietary phosphorus level and phytase inclusion on weaner pig performance and subsequent bone development
Livestock Science 134 (2010) 215–217
Contents lists available at ScienceDirect
Livestock Science j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / l i v s c i
Effect of dietary phosphorus level and phytase inclusion on weaner pig performance and subsequent bone development☆ P.F. Varley a, P.B. Lynch b, J.J. Callan a, J.V. O'Doherty a,⁎ a b
University College Dublin, School of Agriculture, Food Science and Veterinary Medicine, Lyons Research Farm Newcastle, Co. Dublin, Ireland Pig Production Department, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland
a r t i c l e Keywords: Phytase Phosphorus Faecal score Bone
i n f o
a b s t r a c t A 3 × 2 factorial experiment was used to evaluate the response of weaner pigs (11 kg in body weight) to 3 concentrations of dietary phosphorus (P) (4.5, 5.5 and 6.4 g/kg total P) and 2 concentrations of phytase (0 and 500 FTU/kg) on pig performance, faecal score and bone development (8 replicates/treatment, 2 pigs/replicate = 96 pigs). Bone samples were collected from 48 pigs (8/treatment) at the end of the weaner performance study (30 kg body weight). The remaining 48 pigs were then offered a commercial grower and finisher diet with 6 and 5.5 g/kg P respectively until slaughter at 100 kg. In the weaner pig performance study faecal score was decreased as the dietary P concentration decreased (P b 0.001). Dietary phytase supplementation improved the feed conversion ratio of weaner pigs (P b 0.05). Weaner pig bone ash, calcium (Ca) and P concentrations (P b 0.05) was increased as the dietary P concentration increased. Offering diets with phytase (P b 0.001) and increased P concentration (P b 0.05) during the weaner stage resulted in the pig at slaughter having increased bone ash, Ca and P concentrations. In conclusion, the inclusion of phytase in weaner pig diets may alleviate the use of high P diets. There was no performance advantage to feeding high P diets during the weaner stage; however feeding a high P diet resulted in the pig at 100 kg body weight having increased bone ash, Ca and P concentrations. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Most of the phosphorus (P) in cereals used in swine feeds is complexed with other minerals in phytate molecules (Mroz et al., 1994). With this high level of indigestible P, inorganic P has to be added to the diet in order to compensate for the indigestible fraction. This puts nutritional pressure on the weaner pig due to its high buffering capacity resulting in lower efficiency of digestion and scouring problems (Piva et al., 2002). Maximum performance in weanling pigs may be obtained at P levels below current NRC (1998) recommendations with the inclusion of phytase but it is important to investigate if there is any subsequent negative effect on bone
☆ This paper is part of the special issue entitled “11th International Symposium on Digestive Physiology of Pigs”. ⁎ Corresponding author. Tel.: +353 1 7167128; fax: +353 1 7161103. E-mail address: [email protected] (J.V. O'Doherty). 1871-1413/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2010.06.145
development in the finished pig of feeding low P diets during the weanling period. The hypothesis of this study is that feeding the weaner pig (11–30 kg) a low P diet with exogenous phytase will improve pig health and feed efficiency. It is also hypothesized that feeding the low P diet during the weaner stage will have little impact on pig performance or bone development and integrity during the finisher stage (30–100 kg). 2. Materials and methods The experiment was designed as a 3 × 2 factorial to evaluate the response of weanling pigs to three concentrations of total P (tP) (4.5, 5.5, 6.4 g/kg) and two concentrations of phytase Aspergillus niger (Natuphos — BASF Corporation) (0 and 500 FTU/kg). Diets were formulated to have identical concentrations of digestible energy (16 MJ/kg) and ileal digestible lysine (NRC, 1998). The ingredient composition
216
P.F. Varley et al. / Livestock Science 134 (2010) 215–217
and chemical analysis of the experimental diets are presented in Table 1. Weaner pigs were blocked on the basis of initial body weight and assigned to one of 6 dietary treatments and housed in pairs of 2 on fully slatted floors (1.68 m × 1.22 m). Six treatments × two pigs/pen× eight replicates = 96 pigs. Bone samples were collected from 48 pigs at the end of the weaner stage (8 per treatment). Weaner pigs were observed daily for clinical signs of diarrhea during the performance experiment and a scoring system was applied to indicate the presence and severity of this as described by Pierce et al. (2005). 2.1. Combined grower and finisher pig management On completion of the weaner study the remaining 48 pigs were moved to a grower facility and offered a commercial grower diet containing 6.0 g/kg tP for 30 days until they reached an average body weight of 55 kg. The pigs were then offered a commercial finisher diet containing 5.5 g/kg tP for 70 days until they reached an average body weight of 100 kg. Bone samples were collected from 48 pigs at the end of the finisher stage (8 per treatment). 2.2. Laboratory analysis Proximate analysis of diets for dry matter and ash was carried out according to AOAC (1995). The nitrogen content of feed was determined using the LECO FP 528 instrument (Leco Instruments, Ltd, Cheshire, UK). The gross energy of feed samples was determined using a Parr 1201 oxygen bomb calorimeter (Parr, Moline, Illinois, USA). The dietary concentrations of lysine, threonine, tryptophan, methionine and cysteine were determined by high-performance liquid chro-
Table 1 Composition and chemical analysis of experimental diets. Dietary total P, g/kg
4.5
4.5
5.5
5.5
6.4
6.4
Natuphos phytase (500 FTU/kg feed)
−
+
−
+
−
+
400.0 283.4 180.0 100.0 10.0 4.0 1.5 1.5 2.5 11.0 3.0 3.0
400.0 278.5 180.0 100.0 10.0 4.0 1.5 1.5 7.5 11.0 3.0 3.0
400.0 278.4 180.0 100.0 10.0 4.0 1.5 1.5 7.5 11.0 3.0 3.0
400.0 273.5 180.0 100.0 10.0 4.0 1.5 1.5 12.5 11.0 3.0 3.0
400.0 273.4 180.0 100.0 10.0 4.0 1.5 1.5 12.5 11.0 3.0 3.0
Composition (g/kg) Wheat 400.0 Barley 283.5 Soya bean meal 180.0 Soya full fat 100.0 Soya oil 10.0 L-Lysine 4.0 DL-Methionine 1.5 L-Threonine 1.5 Dicalcium phosphate 2.5 Ground limestone 11.0 Salt 3.0 Vitamins & Minerals 3.0 Analysed composition (g/kg) Dry matter 880.2 Crude protein (Nx6.25) 197.4 Gross energy (MJ/kg) 17.0 Phosphorus 4.2 Calcium 7.4 Lysine 13.1 Methionine & cystine 7.9 Threonine 8.6 Tryptophan 2.5
875.3 878.3 879.7 881.0 880.8 197.4 197.3 198.5 195.0 190.2 17.0 16.7 16.9 16.5 16.7 4.2 4.8 5.0 5.9 6.1 7.6 8.4 8.5 9.5 9.8 13.1 13.2 13.1 13.3 13.1 7.9 7.9 7.9 7.9 7.9 8.6 8.5 8.5 8.5 8.5 2.5 2.4 2.5 2.5 2.5
matography (Iwaki et al., 1987). The third and fourth metacarpals from the front right foot was analysed for ash, Ca and P as described by Brady et al. (2003). 2.3. Statistical analysis The performance and bone studies were analysed as a 3 × 2 factorial using the General Linear Model of the Statistical Analysis Systems Institute (1985). The statistical model for weaner pig performance and bone analysis included the main effects of P concentration, phytase supplementation, block and the interaction between P and phytase. The bone data were adjusted for slaughter-weight by covariance. All the data were checked initially for normality using the PROC Univariate procedure in SAS (1985). The Tukey test was used to check for differences between means. 3. Results 3.1. Performance study Pigs offered the phytase based diets had an improved overall FCR compared to those offered the diets without phytase (P b 0.05) (Table 2). The pigs offered both the low and medium P diets had a lower (harder) faecal score compared with the pigs offered the high P diets during days 0–34 (P b 0.001) as shown in Table 2. Neither phytase inclusion nor P concentration in the diet during the weaner stage had a significant effect on finisher pig performance or carcass characteristics when slaughtered at 100 kg body weight (data not presented). 3.2. Bone analysis There was a significant P effect on bone ash, Ca, and P concentrations (Table 2) at the end of the weaner stage. Pigs offered the high P diet had a higher (P b 0.05) concentration of bone ash, Ca and P than those offered the medium and low P diets. Pigs offered the low P diets during the weaner trial had a lower (P b 0.05) bone ash, P and Ca concentrations than those offered the medium and high P diets when slaughtered at 100 kg. Phytase inclusion in the diet, during the weaner trial, increased (P b 0.001) bone ash, P and Ca concentrations at 100 kg body weight (Table 2). 4. Discussion Pigs offered the high P diet had a higher faecal score than those offered the medium and low P diet during the 5 week performance experiment. This is probably due to the buffering capacity of the dicalcium phosphate. Buffering capacity of a diet can be described as the resistance of a diet to pH reduction by gastric hydrochloric acid. Because of the high buffering capacity of limestone and inorganic phosphate sources, increasing the dietary inclusion concentration of these ingredients in diets fed to weanling pigs can increase scouring (Stein, 2002) which is critical in the absence of in feed antibiotics. In the current study pigs offered phytase and increasing concentration of P in the diet during the weaner experiment had a higher concentration of bone ash, Ca and P
P.F. Varley et al. / Livestock Science 134 (2010) 215–217
217
Table 2 Effect of phosphorus concentration and phytase inclusion on weaner pig performance, faecal score and bone measurements (LSM ± SEM). Dietary total P, g/kg
N
SEM
Phytase, 500 FTU/kg
4.5
5.5
6.4
−
+
16
16
16
24
24
Weaner pig performance (days 0–34) Average daily gain (kg/day) 0.539 Feed intake (kg/day) 1.039 Feed conversion ratio (kg/kg) 1.95 Faecal score a 2.1 Bone measurements at 30 kg body weight Bone ash (g/kg) 344.6 Bone P (g/kg) 55.7 Bone Ca (g/kg) 123.5 Bone measurements at 100 kg body weight Bone ash (g/kg) 505.2 Bone P (g/kg) 85.9 Bone Ca (g/kg) 181.9
0.577 1.081 1.91 2.0
0.558 1.068 1.94 2.8
0.015 0.024 0.051 0.069
0.553 1.081 1.99 2.3
0.564 1.044 1.88 2.3
SEM
Significance* P
Phy
0.012 0.019 0.041 0.056
ns ns ns ***
ns ns * ns
354.6 57.7 125.9
386.3 62.5 140.0
10.771 1.911 4.284
357.6 58.1 129.1
366.0 59.2 130.5
8.802 1.563 3.502
* * *
ns ns ns
526.9 89.6 189.7
532.3 90.5 191.6
7.754 1.321 2.793
500.9 85.2 180.3
542.1 92.2 195.2
6.251 1.073 2.253
* * *
*** *** ***
*In the absence of an interaction main effects are presented. P = phosphorus; Ca = Calcium; Phy = phytase. Probability of significance: * = P b 0.05; *** = P b 0.001; ns, not significant, P N 0.05. a 1 = hard faeces and 5 = watery, mucous-like faeces.
concentrations when slaughtered at 100 kg when compared to pigs offered diets without the inclusion of phytase and diets decreasing in P concentration. These findings indicate that the effects of phytase and P concentrations in the weaner diet continued to be expressed in the bone when slaughtered at 100 kg. The weaner stage is the critical period for bone mineral accrual given that when the pig reaches 56 weeks of age bone volume fraction peaks although 60% of this volume is achieved when the pig reaches 14 weeks of age (Tanck et al., 2001). Optimising P nutrition during the weaner period maybe seen as a method of maximising subsequent bone mineral concentrations.
5. Conclusion Including phytase in weaner pig diets may alleviate the use of high P diets and result in the pig having increased bone ash, Ca and P concentrations at bacon weight. There was no performance advantage to feeding high P diets during the weaner stage; however feeding a high P diet resulted in the pig at 100 kg body weight having increased bone ash, Ca and P concentrations.
Conflict of interest None of the authors had any conflict of interest in this work.
Acknowledgements Funding for this research was provided under the National Development Plan, through the Research Stimulus Fund, administered by the Irish Department of Agriculture, Fisheries & Food. References Association of Official Analytical Chemists, 1995. Official Methods of Analysis. AOAC, Washington DC, USA. Brady, S.M., Callan, J.J., Cowan, D., McGrane, M., O'Doherty, J.V., 2003. Effect of two microbial phytases on the performance and nutrient retention on grower-finisher pigs fed barley–maize–soyabean meal-based diets. Irish J. Agric. Food Res. 42, 101–117. Institute SAS, 1985. Statistical Analysis Systems. In SAS Cary, NC. Iwaki, K., Nimura, N., Hiraga, Y., Kinoshita, T., Takeda, K., Ogura, H., 1987. Amino acid analysis by reversed-phase high-performance liquid chromatography. J. Chromatogr. Sci. 407, 273–379. Mroz, Z., Jongbloed, A.W., Kemme, P.A., 1994. Apparent digestibility and retention of nutrients bound to phytate complexes as influenced by microbial phytase and feeding regimen in pigs. J. Anim. Sci. 72, 126–132. NRC, 1998. Nutrient Requirements of Swine10th edition. National Academy Press, Washington, D.C.. 20418. Pierce, K.M., Callan, J.J., McCarthy, P., O'Doherty, J.V., 2005. Performance of weanling pigs offered low or high lactose diets supplemented with avilamycin or inulin. Anim. Sci. 80, 313–318. Piva, A., Casadei, G., Biagi, G., 2002. An organic acid blend can modulate swine intestinal fermentation and reduce microbial proteolysis. Can. J. Anim. Sci. 82, 527–532. Stein, H.H., 2002. Experience of feeding pigs without antibiotics: an European perspective. Anim. Biotechnol. 13, 85–95. Tanck, E., Homminga, J., van Lenthe, G.H., Huiskes, R., 2001. Increase in bone volume fraction precedes architectural adaptation in growing bone. Bone 28, 650–654.
Contents lists available at ScienceDirect
Livestock Science j o u r n a l h o m e p a g e : w w w. e l s ev i e r. c o m / l o c a t e / l i v s c i
Effect of dietary phosphorus level and phytase inclusion on weaner pig performance and subsequent bone development☆ P.F. Varley a, P.B. Lynch b, J.J. Callan a, J.V. O'Doherty a,⁎ a b
University College Dublin, School of Agriculture, Food Science and Veterinary Medicine, Lyons Research Farm Newcastle, Co. Dublin, Ireland Pig Production Department, Teagasc, Moorepark, Fermoy, Co. Cork, Ireland
a r t i c l e Keywords: Phytase Phosphorus Faecal score Bone
i n f o
a b s t r a c t A 3 × 2 factorial experiment was used to evaluate the response of weaner pigs (11 kg in body weight) to 3 concentrations of dietary phosphorus (P) (4.5, 5.5 and 6.4 g/kg total P) and 2 concentrations of phytase (0 and 500 FTU/kg) on pig performance, faecal score and bone development (8 replicates/treatment, 2 pigs/replicate = 96 pigs). Bone samples were collected from 48 pigs (8/treatment) at the end of the weaner performance study (30 kg body weight). The remaining 48 pigs were then offered a commercial grower and finisher diet with 6 and 5.5 g/kg P respectively until slaughter at 100 kg. In the weaner pig performance study faecal score was decreased as the dietary P concentration decreased (P b 0.001). Dietary phytase supplementation improved the feed conversion ratio of weaner pigs (P b 0.05). Weaner pig bone ash, calcium (Ca) and P concentrations (P b 0.05) was increased as the dietary P concentration increased. Offering diets with phytase (P b 0.001) and increased P concentration (P b 0.05) during the weaner stage resulted in the pig at slaughter having increased bone ash, Ca and P concentrations. In conclusion, the inclusion of phytase in weaner pig diets may alleviate the use of high P diets. There was no performance advantage to feeding high P diets during the weaner stage; however feeding a high P diet resulted in the pig at 100 kg body weight having increased bone ash, Ca and P concentrations. © 2010 Elsevier B.V. All rights reserved.
1. Introduction Most of the phosphorus (P) in cereals used in swine feeds is complexed with other minerals in phytate molecules (Mroz et al., 1994). With this high level of indigestible P, inorganic P has to be added to the diet in order to compensate for the indigestible fraction. This puts nutritional pressure on the weaner pig due to its high buffering capacity resulting in lower efficiency of digestion and scouring problems (Piva et al., 2002). Maximum performance in weanling pigs may be obtained at P levels below current NRC (1998) recommendations with the inclusion of phytase but it is important to investigate if there is any subsequent negative effect on bone
☆ This paper is part of the special issue entitled “11th International Symposium on Digestive Physiology of Pigs”. ⁎ Corresponding author. Tel.: +353 1 7167128; fax: +353 1 7161103. E-mail address: [email protected] (J.V. O'Doherty). 1871-1413/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.livsci.2010.06.145
development in the finished pig of feeding low P diets during the weanling period. The hypothesis of this study is that feeding the weaner pig (11–30 kg) a low P diet with exogenous phytase will improve pig health and feed efficiency. It is also hypothesized that feeding the low P diet during the weaner stage will have little impact on pig performance or bone development and integrity during the finisher stage (30–100 kg). 2. Materials and methods The experiment was designed as a 3 × 2 factorial to evaluate the response of weanling pigs to three concentrations of total P (tP) (4.5, 5.5, 6.4 g/kg) and two concentrations of phytase Aspergillus niger (Natuphos — BASF Corporation) (0 and 500 FTU/kg). Diets were formulated to have identical concentrations of digestible energy (16 MJ/kg) and ileal digestible lysine (NRC, 1998). The ingredient composition
216
P.F. Varley et al. / Livestock Science 134 (2010) 215–217
and chemical analysis of the experimental diets are presented in Table 1. Weaner pigs were blocked on the basis of initial body weight and assigned to one of 6 dietary treatments and housed in pairs of 2 on fully slatted floors (1.68 m × 1.22 m). Six treatments × two pigs/pen× eight replicates = 96 pigs. Bone samples were collected from 48 pigs at the end of the weaner stage (8 per treatment). Weaner pigs were observed daily for clinical signs of diarrhea during the performance experiment and a scoring system was applied to indicate the presence and severity of this as described by Pierce et al. (2005). 2.1. Combined grower and finisher pig management On completion of the weaner study the remaining 48 pigs were moved to a grower facility and offered a commercial grower diet containing 6.0 g/kg tP for 30 days until they reached an average body weight of 55 kg. The pigs were then offered a commercial finisher diet containing 5.5 g/kg tP for 70 days until they reached an average body weight of 100 kg. Bone samples were collected from 48 pigs at the end of the finisher stage (8 per treatment). 2.2. Laboratory analysis Proximate analysis of diets for dry matter and ash was carried out according to AOAC (1995). The nitrogen content of feed was determined using the LECO FP 528 instrument (Leco Instruments, Ltd, Cheshire, UK). The gross energy of feed samples was determined using a Parr 1201 oxygen bomb calorimeter (Parr, Moline, Illinois, USA). The dietary concentrations of lysine, threonine, tryptophan, methionine and cysteine were determined by high-performance liquid chro-
Table 1 Composition and chemical analysis of experimental diets. Dietary total P, g/kg
4.5
4.5
5.5
5.5
6.4
6.4
Natuphos phytase (500 FTU/kg feed)
−
+
−
+
−
+
400.0 283.4 180.0 100.0 10.0 4.0 1.5 1.5 2.5 11.0 3.0 3.0
400.0 278.5 180.0 100.0 10.0 4.0 1.5 1.5 7.5 11.0 3.0 3.0
400.0 278.4 180.0 100.0 10.0 4.0 1.5 1.5 7.5 11.0 3.0 3.0
400.0 273.5 180.0 100.0 10.0 4.0 1.5 1.5 12.5 11.0 3.0 3.0
400.0 273.4 180.0 100.0 10.0 4.0 1.5 1.5 12.5 11.0 3.0 3.0
Composition (g/kg) Wheat 400.0 Barley 283.5 Soya bean meal 180.0 Soya full fat 100.0 Soya oil 10.0 L-Lysine 4.0 DL-Methionine 1.5 L-Threonine 1.5 Dicalcium phosphate 2.5 Ground limestone 11.0 Salt 3.0 Vitamins & Minerals 3.0 Analysed composition (g/kg) Dry matter 880.2 Crude protein (Nx6.25) 197.4 Gross energy (MJ/kg) 17.0 Phosphorus 4.2 Calcium 7.4 Lysine 13.1 Methionine & cystine 7.9 Threonine 8.6 Tryptophan 2.5
875.3 878.3 879.7 881.0 880.8 197.4 197.3 198.5 195.0 190.2 17.0 16.7 16.9 16.5 16.7 4.2 4.8 5.0 5.9 6.1 7.6 8.4 8.5 9.5 9.8 13.1 13.2 13.1 13.3 13.1 7.9 7.9 7.9 7.9 7.9 8.6 8.5 8.5 8.5 8.5 2.5 2.4 2.5 2.5 2.5
matography (Iwaki et al., 1987). The third and fourth metacarpals from the front right foot was analysed for ash, Ca and P as described by Brady et al. (2003). 2.3. Statistical analysis The performance and bone studies were analysed as a 3 × 2 factorial using the General Linear Model of the Statistical Analysis Systems Institute (1985). The statistical model for weaner pig performance and bone analysis included the main effects of P concentration, phytase supplementation, block and the interaction between P and phytase. The bone data were adjusted for slaughter-weight by covariance. All the data were checked initially for normality using the PROC Univariate procedure in SAS (1985). The Tukey test was used to check for differences between means. 3. Results 3.1. Performance study Pigs offered the phytase based diets had an improved overall FCR compared to those offered the diets without phytase (P b 0.05) (Table 2). The pigs offered both the low and medium P diets had a lower (harder) faecal score compared with the pigs offered the high P diets during days 0–34 (P b 0.001) as shown in Table 2. Neither phytase inclusion nor P concentration in the diet during the weaner stage had a significant effect on finisher pig performance or carcass characteristics when slaughtered at 100 kg body weight (data not presented). 3.2. Bone analysis There was a significant P effect on bone ash, Ca, and P concentrations (Table 2) at the end of the weaner stage. Pigs offered the high P diet had a higher (P b 0.05) concentration of bone ash, Ca and P than those offered the medium and low P diets. Pigs offered the low P diets during the weaner trial had a lower (P b 0.05) bone ash, P and Ca concentrations than those offered the medium and high P diets when slaughtered at 100 kg. Phytase inclusion in the diet, during the weaner trial, increased (P b 0.001) bone ash, P and Ca concentrations at 100 kg body weight (Table 2). 4. Discussion Pigs offered the high P diet had a higher faecal score than those offered the medium and low P diet during the 5 week performance experiment. This is probably due to the buffering capacity of the dicalcium phosphate. Buffering capacity of a diet can be described as the resistance of a diet to pH reduction by gastric hydrochloric acid. Because of the high buffering capacity of limestone and inorganic phosphate sources, increasing the dietary inclusion concentration of these ingredients in diets fed to weanling pigs can increase scouring (Stein, 2002) which is critical in the absence of in feed antibiotics. In the current study pigs offered phytase and increasing concentration of P in the diet during the weaner experiment had a higher concentration of bone ash, Ca and P
P.F. Varley et al. / Livestock Science 134 (2010) 215–217
217
Table 2 Effect of phosphorus concentration and phytase inclusion on weaner pig performance, faecal score and bone measurements (LSM ± SEM). Dietary total P, g/kg
N
SEM
Phytase, 500 FTU/kg
4.5
5.5
6.4
−
+
16
16
16
24
24
Weaner pig performance (days 0–34) Average daily gain (kg/day) 0.539 Feed intake (kg/day) 1.039 Feed conversion ratio (kg/kg) 1.95 Faecal score a 2.1 Bone measurements at 30 kg body weight Bone ash (g/kg) 344.6 Bone P (g/kg) 55.7 Bone Ca (g/kg) 123.5 Bone measurements at 100 kg body weight Bone ash (g/kg) 505.2 Bone P (g/kg) 85.9 Bone Ca (g/kg) 181.9
0.577 1.081 1.91 2.0
0.558 1.068 1.94 2.8
0.015 0.024 0.051 0.069
0.553 1.081 1.99 2.3
0.564 1.044 1.88 2.3
SEM
Significance* P
Phy
0.012 0.019 0.041 0.056
ns ns ns ***
ns ns * ns
354.6 57.7 125.9
386.3 62.5 140.0
10.771 1.911 4.284
357.6 58.1 129.1
366.0 59.2 130.5
8.802 1.563 3.502
* * *
ns ns ns
526.9 89.6 189.7
532.3 90.5 191.6
7.754 1.321 2.793
500.9 85.2 180.3
542.1 92.2 195.2
6.251 1.073 2.253
* * *
*** *** ***
*In the absence of an interaction main effects are presented. P = phosphorus; Ca = Calcium; Phy = phytase. Probability of significance: * = P b 0.05; *** = P b 0.001; ns, not significant, P N 0.05. a 1 = hard faeces and 5 = watery, mucous-like faeces.
concentrations when slaughtered at 100 kg when compared to pigs offered diets without the inclusion of phytase and diets decreasing in P concentration. These findings indicate that the effects of phytase and P concentrations in the weaner diet continued to be expressed in the bone when slaughtered at 100 kg. The weaner stage is the critical period for bone mineral accrual given that when the pig reaches 56 weeks of age bone volume fraction peaks although 60% of this volume is achieved when the pig reaches 14 weeks of age (Tanck et al., 2001). Optimising P nutrition during the weaner period maybe seen as a method of maximising subsequent bone mineral concentrations.
5. Conclusion Including phytase in weaner pig diets may alleviate the use of high P diets and result in the pig having increased bone ash, Ca and P concentrations at bacon weight. There was no performance advantage to feeding high P diets during the weaner stage; however feeding a high P diet resulted in the pig at 100 kg body weight having increased bone ash, Ca and P concentrations.
Conflict of interest None of the authors had any conflict of interest in this work.
Acknowledgements Funding for this research was provided under the National Development Plan, through the Research Stimulus Fund, administered by the Irish Department of Agriculture, Fisheries & Food. References Association of Official Analytical Chemists, 1995. Official Methods of Analysis. AOAC, Washington DC, USA. Brady, S.M., Callan, J.J., Cowan, D., McGrane, M., O'Doherty, J.V., 2003. Effect of two microbial phytases on the performance and nutrient retention on grower-finisher pigs fed barley–maize–soyabean meal-based diets. Irish J. Agric. Food Res. 42, 101–117. Institute SAS, 1985. Statistical Analysis Systems. In SAS Cary, NC. Iwaki, K., Nimura, N., Hiraga, Y., Kinoshita, T., Takeda, K., Ogura, H., 1987. Amino acid analysis by reversed-phase high-performance liquid chromatography. J. Chromatogr. Sci. 407, 273–379. Mroz, Z., Jongbloed, A.W., Kemme, P.A., 1994. Apparent digestibility and retention of nutrients bound to phytate complexes as influenced by microbial phytase and feeding regimen in pigs. J. Anim. Sci. 72, 126–132. NRC, 1998. Nutrient Requirements of Swine10th edition. National Academy Press, Washington, D.C.. 20418. Pierce, K.M., Callan, J.J., McCarthy, P., O'Doherty, J.V., 2005. Performance of weanling pigs offered low or high lactose diets supplemented with avilamycin or inulin. Anim. Sci. 80, 313–318. Piva, A., Casadei, G., Biagi, G., 2002. An organic acid blend can modulate swine intestinal fermentation and reduce microbial proteolysis. Can. J. Anim. Sci. 82, 527–532. Stein, H.H., 2002. Experience of feeding pigs without antibiotics: an European perspective. Anim. Biotechnol. 13, 85–95. Tanck, E., Homminga, J., van Lenthe, G.H., Huiskes, R., 2001. Increase in bone volume fraction precedes architectural adaptation in growing bone. Bone 28, 650–654.