Table 9.

Effect of animal species and feedlot period on excretion of urinary creatinine, purine derivatives, and urea obtained from total collections after 4-h intervals

Item1	Species		Days in feedlot			SEM	P value1
	Goat	Sheep	28	56	84		Species	DF	T	S × DF	S × T	DF × T	S × DF × T
Creatinine2
mg/d	170.56	168.74	117.36	190.63	166.14	8.51	0.93	<0.01	0.27	0.62	0.23	0.46	0.07
mg/kg BW	6.05	5.31	5.05	6.50	5.48	0.25	0.16	0.07	0.41	0.72	0.43	0.51	0.17
mmol/kg BW0.75	0.10	0.09	0.08	0.11	0.10	0.01	0.29	0.04	0.39	0.74	0.38	0.50	0.13
Purine derivatives3
mmol/d	1.55	2.10	1.55	1.73	2.20	0.11	0.01	0.04	0.02	0.64	0.01	0.18	0.08
mmol/kg BW0.75	0.13	0.16	0.15	0.14	0.15	0.01	<0.01	0.63	0.02	0.07	0.03	0.18	0.06
Urea4
g/d	0.71	1.03	0.63	0.97	1.00	0.05	<0.01	<0.01	0.03	0.65	0.52	0.14	0.18
mg/kg BW	24.72	34.13	28.12	32.54	27.62	1.45	<0.01	0.38	0.02	0.24	0.61	0.10	0.11
Ratios
PD:C5	1.60	2.19	1.99	2.01	1.68	0.09	<0.01	0.31	0.76	0.32	0.82	0.68	0.12
U:C6	3.90	5.74	4.50	5.59	4.37	0.21	<0.01	0.06	0.01	<0.01	0.96	0.45	0.44

¹DF = days in feedlot; T = time of sampling comprising 4-h urinary collections along the day; S × DF = interaction between animal species and days in feedlot; DF × T = interaction between days in feedlot and time of sampling; S × DF × T = interaction between species, days in feedlot, and time of sampling.

²Creatinine (mg/d): linear effect: P = 0.02 and quadratic effect: P = 0.14; creatinine (mmol/kg BW^0.75): linear effect: P = 0.13 and quadratic effect: P = 0.04.

³Purine derivatives (mmol/d): linear effect: P = 0.01 and quadratic effect: P = 0.50.

⁴Urea (g/d): linear effect: P < 0.01 and quadratic effect: P = 0.18.

⁵PD:C = purine derivatives:creatinine ratio.

⁶U:C = urea:creatinine ratio.