Influences of dietary-reduced nitrogen (N) and phosphorus (P) on chemical body composition, N and P retention and health traits of contemporary barrows

Figures & data

Figure 1. Procedures of the body fractionation of 8 barrows (average live weight 123.3 ± 7.5 kg). The four fractions are highlighted in grey.

Table 1. Relative organ weights [g/kg live weight] of barrows at slaughter fed the control diet (CON, n = 4) or the diet with reduced nitrogen and phosphorus concentration (NPred, n = 4). Data are presented as means ± standard deviation.

	CON	NPred	p-values
Lung	5.8 ± 1.2	6.8 ± 2.0	0.391
Heart	3.6 ± 0.5	3.7 ± 0.2	0.809
Liver	14.8 ± 0.7	15.8 ± 0.6	0.061
Pancreas	1.9 ± 0.2	1.9 ± 0.2	0.452
Kidneys	2.8 ± 0.4	2.5 ± 0.3	0.239
Spleen	1.7 ± 0.2	1.6 ± 0.2	0.858
Stomach^†	6.1 ± 0.8	5.8 ± 0.5	0.620
Small intestine^†	15.9 ± 1.4	15.4 ± 0.9	0.560
Large intestine^†	15.0 ± 1.3	16.6 ± 2.5	0.283

^†Weighed without content of gastrointestinal tract.

Pigs were fed in a 3-phased feeding regimen (3 weeks/phase). Initial live weight (LW) at the beginning of the experiment was 61.5 ± 2.1 kg kg. Pigs were slaughtered with an average LW of 123.3 ± 7.5 kg.

Table 2. Clinical-chemical traits in blood serum of barrows at slaughter fed the control diet (CON, n = 3) and the diet with reduced nitrogen and phosphorus concentrations (NPred, n = 4). Data are presented as means ± standard deviation.

	CON	NPred	p-values
Protein metabolism
Total protein [g/l]	68.4 ± 3.6	65.4 ± 3.7	0.324
Albumin [g/l]	41.2 ± 2.5	36.8 ± 1.3	0.025
Creatinine [µmol/l]	137.1 ± 21.4	158.1 ± 26.2	0.310
Urea [mmol/l]	5.1 ± 0.66	3.8 ± 0.2	0.013
Energy metabolism
Cholesterol [mmol/l]	2.9 ± 0.5	2.9 ± 0.2	0.935
Triglycerides [mmol/l]	0.3 ± 0.1	0.3 ± 0.1	0.981
Glucose [mmol/l]	5.7 ± 0.6	6.2 ± 1.0	0.453
Liver integrity
ALP^† [U/l]	126.6 ± 47.5	133.1 ± 17.0	0.805
ALT^§ [U/l]	73.6 ± 8.9	70.9 ± 11.8	0.750
AST^# [U/l]	42.3 ± 10.6	49.4 ± 26.7	0.688
GGT^¶ [U/l]	39.0 ± 6.5	42.6 ± 13.3	0.688
GLDH^$ [U/l]	< LOQ^+*	< LOQ+	–
Bilirubin total [µmol/l]	1.3 ± 0.3	1.3 ± 0.4	0.762
Bilirubin direct [µmol/l]	0.6 ± 0.1	0.7 ± 0.3	0.722
Electrolytes
Calcium [mmol/l]	2.7 ± 0.1	2.5 ± 0.1	0.125
Chloride [mmol/l]	104.4 ± 1.8	104.5 ± 1.0	0.981
Phosphorus [mmol/l]	2.8 ± 0.1	3.0 ± 0.3	0.209
Potassium [mmol/l]	8.9 ± 1.7	10.2 ± 0.9	0.258
Sodium [mmol/l]	138.1 ± 0.9	136.4 ± 1.2	0.097

^†ALP, alkaline phosphatase; ^§ALT, alanine aminotransferase; ^#AST, aspartate aminotransferase; ^¶GGT, gamma-glutamyl-transferase; ^$GLDH, glutamate dehydrogenase; ⁺LOQ, limit of quantification = 1.8 U/l; *GLDH concentration of one CON-fed pig was above LOQ (3.27 U/l).

Pigs were fed in a 3-phased feeding regimen (3 weeks/phase). Initial live weight (LW) at the beginning of the experiment was 61.5 ± 2.1 kg kg. Pigs were slaughtered with an average LW of 123.3 ± 7.5 kg.

Table 3. Empty body weight (EBW), carcass weight, dressing percentage and fractions of full body analysis of barrows at slaughter fed the control diet (CON, n = 4) and the diet with reduced nitrogen and phosphorus concentrations (NPred, n = 4). Data are presented as means ± standard deviation.

	CON	NPred	p-values
EBW [kg]	111.9 ± 7.8	113.5 ± 4.2	0.734
EBW/LW^† [%]	90.9 ± 1.5	92.0 ± 0.6	0.207
Carcass weight [kg]	96.9 ± 7.0	97.8 ± 3.7	0.835
Dressing percentage [%]	78.7 ± 1.2	79.3 ± 0.4	0.367
Fractions of full body analysis [g/kg EBW]
Blood, organs	134.3 ± 4.9	138.7 ± 3.6	0.199
Musculature	518.4 ± 25.7	505.7 ± 24.8	0.501
Bones	86.3 ± 4.3	81.6 ± 2.3	0.101
Fat, skin, hooves	261.0 ± 24.5	274.1 ± 22.1	0.457

^†LW, live weight.

Pigs were fed in a 3-phased feeding regimen (3 weeks/phase). Initial live weight (LW) at the beginning of the experiment was 61.5 ± 2.1 kg kg. Pigs were slaughtered with an average LW of 123.3 ± 7.5 kg.

Table 4. Chemical body composition of barrows at slaughter fed the control diet (CON, n = 4) and the diet with reduced nitrogen and phosphorus concentrations (NPred, n = 4). Data are presented as means ± standard deviation.

	CON	NPred	p-values
Nutrient concentration [g/kg EBW^†]
Dry matter	485.0 ± 9.5	486.2 ± 19.3	0.919
Crude ash	28.3 ± 2.0	26.7 ± 0.3	0.199
Crude fat	294.6 ± 11.1	298.0 ± 18.9	0.767
Crude protein^$	152.9 ± 6.4	145.6 ± 2.1	0.073
Nitrogen	24.5 ± 1.0	23.3 ± 0.3	0.073
Gross energy^§ [MJ/kg EBW^†]	15.3 ± 0.5	15.3 ± 0.7	0.932
Phosphorus	5.5 ± 0.4	5.2 ± 0.1	0.164
Calcium	9.0 ± 0.7	8.2 ± 0.3	0.077

^†EBW, empty body weight; ^$Nitrogen concentration was analysed and multiplied with factor 6.25 for crude protein concentration; ^§Calculation according to (GfE 2006).

Pigs were fed in a 3-phased feeding regimen (3 weeks/phase). Initial live weight (LW) at the beginning of the experiment was 61.5 ± 2.1 kg kg. Pigs were slaughtered with an average LW of 123.3 ± 7.5 kg.

Figure 2. Regression between calculated and analysed body crude protein (CP) concentration of barrows from the present experiment (circle), a performance trial (plus) and a balance trial (cross) of Haude (2003). For calculation, Equation 8 of GfE (2006) was used. The black line shows the regression line, symbols show the observations (n = 71), grey shaded area shows the 95% confidence interval, the dashed lines the 95% prediction limits. The regression model is y = 0.53 + 1.01·x with RMSE = 0.92 kg and adjusted r2 = 0.36.

Table 5. Initial body crude protein (CP) concentration and calculated nitrogen (N) and phosphorus (P) retention of barrows fed the control diet (CON, n = 4) and the diet with reduced nitrogen and phosphorus concentrations (NPred, n = 4). Results are presented as means ± standard deviation.

	CON	NPred	p-values
Initial nutrient concentration [g/kg EBW^†]
CP	162.8 ± 0.1	162.7 ± 0.2	0.667
P	5.73*		–
N retention
kg	1.2 ± 0.2	1.2 ± 0.1	0.641
g/d	19.7 ± 3.1	18.8 ± 1.8	0.641
g/kg LW^0.67/d^§	0.78 ± 0.09	0.75 ± 0.06	0.563
P retention
g	289.9 ± 45.7	256.5 ± 23.0	0.240
g/d	4.6 ± 0.7	4.1 ± 0.4	0.240
mg/kg LW^0.67/d^§	182.5 ± 24.4	161.6 ± 11.6	0.172

†EBW, empty body weight; *data on initial P concentration were obtained from Ruiz-Ascacibar et al. (2019); §LW^0.67 = metabolic live weight.

Pigs were fed in a 3-phased feeding regimen (3 weeks/phase). Initial live weight (LW) at the beginning of the experiment was 61.5 ± 2.1 kg. Pigs were slaughtered with an average LW of 123.3 ± 7.5 kg.

Figure 3. Fractions of full body analysis relative to carcass weight of pigs fed the control diet (CON, n = 4) and the diet with reduced nitrogen and phosphorus concentrations (NPred, n = 4).

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