Simple methods to estimate the maintenance feed requirement of small ruminants with different levels of feed restriction

Figures & data

Table 1. Composition of grass hay consumed by KAT sheep and SPA goat wethers.

Item	% DM	SEM
Ash	8.6	0.05
CP	7.8	0.20
NDF	69.5	0.39
Acid detergent fibre	41.5	0.49
Acid detergent lignin	8.1	0.22

Note: 15 weekly composite samples formed from samples collected daily (two preliminary period, five maintenance phase, and eight restriction phase).

Figure 1. Daily dry matter offered (DMO) and intake (DMI) by KAT sheep and SPA goat wethers during the 5-week maintenance phase to estimate the feed requirement for maintenance with feed offered near the maintenance requirement.

Figure 2. BW during the 5-week maintenance phase to determine the feed requirement for maintenance with feed offered near the maintenance requirement. Panel A: KAT sheep wethers. Panel B: SPA goat wethers.

Table 2. Equations for the linear regression of DMI against ADG of individual animals in weeks 3 and 4 of the maintenance phase with feed consumption varied near the maintenance requirement for constant BW^a.

Breed	Animal	Intercept (g/day)		Slope (g/day)			R^2	Mean DMI
		Estimate	SEM	Estimate	SEM	p value^b
Katahdin	130	645	6.0	0.027	0.0229	.293	.217	643
Katahdin	131	599	5.3	0.020	0.0403	.644	.046	598
Katahdin	132	648	12.7	−0.012	0.0575	.842	.009	649
Katahdin	133	615	5.0	−0.002	0.0109	.886	.005	615
Katahdin	134	675	2.3	0.010	0.0111	.414	.137	675
Katahdin	135	666	3.2	−0.017	0.0120	.222	.280	667
Katahdin	136	729	5.9	0.019	0.0251	.475	.106	728
Katahdin	138	646	5.6	−0.008	0.0125	.558	.073	647
Katahdin	140	709	5.4	−0.008	0.0163	.636	.048	709
Katahdin	141	654	2.8	0.005	0.0076	.599	.161	653
Spanish	503	439	28.5	0.035	0.1301	.800	.014	435
Spanish	5031	521	5.9	0.008	0.0264	.776	.018	521
Spanish	5054	498	10.1	0.003	0.1174	.979	<.001	498
Spanish	5056	480	29.1	0.124	0.2090	.578	.066	469
Spanish	5060	517	4.3	0.011	0.0161	.540	.079	516
Spanish	5065	499	3.0	−0.004	0.0162	.821	.011	500
Spanish	5066	465	8.7	0.036	0.0435	.443	.122	463
Spanish	5068	468	9.8	0.075	0.0789	.384	.154	465
Spanish	5085	510	8.9	0.121	0.0672	.130	.396	508
Spanish	5091	480	8.2	0.005	0.0489	.924	.002	480

aIntervals of 2 or 3 days in length.

bp values for difference from 0.

Table 3. Estimates of feed required for maintenance, with feed consumption varied near the maintenance requirement for constant BW based on BW and HE determined from HR and the HE:HR ratio.

Item	KAT sheep		SPA goats		SEM	p values
	BW	HR	BW	HR		Breed	Method	Interaction
DM intake (g/day)	659	630	488	497	14.4	<.001	.498	.201
Maintenance DM intake (g/kg BW^0.75)	52.0	49.8	49.6	50.5	1.11	.425	.539	.164
Maintenance ME intake (kJ/kg BW^0.75)	436	417	415	422	9.3	.425	.539	.164

Note: DM –  dry matter; ME –  metabolizable energy.

Figure 3. BW of individual wethers during the 8-week restriction phase to determine the feed requirement for maintenance with feed restriction. Panel A: KAT sheep and 55% of intake near the maintenance requirement without feed restriction. Panel B: KAT sheep and 70% of intake near the maintenance requirement without feed restriction. Panel C: SPA goats and 55% of intake near the maintenance requirement without feed restriction. Panel D: SPA goats and 70% of intake near the maintenance requirement without feed restriction.

Table 4. BW loss by KAT sheep and SPA goat wethers in different weeks of the feed restriction phase^a as a percentage of initial BW.

Week^b	KAT sheep		SPA goats		SEM	p values
	55%	70%	55%	70%		Breed	Restriction	Interaction
2	13.2^c	7.0^e	7.6^e	7.4^e	0.97	.016	.005	.007
3	13.4^c	6.5^e	7.8^e	7.5^e	1.07	.048	.004	.008
4	13.4^c	6.3^e	8.2^e	7.4^e	1.03	.064	.001	.007
5	15.3^c	6.6^e	9.9^e	8.1^e	1.18	.119	.005	.010
6	15.6^d	7.1^e	11.3^c	8.8^ce	1.14	.287	<.001	.019
7	16.8^d	8.3^e	12.3^c	9.4^ce	1.24	.128	<.001	.038
8	18.4^d	8.7^e	13.4^c	10.6^ce	1.34	.267	<.001	.022

^aFeeding levels were 55 and 70% of feed required for maintenance of each wether based on frequent small changes in feeding levels for constant BW in an earlier phase.

^bAverage BW was determined on day 0, 2, 4, and 7 of each week.

^c,d,eMeans in a row without a common superscript letter differ (p < 0.05).

Table 5. Equations for the linear regression of BW (kg) against day of week 8 of the feed restriction period^a.

Animal type	Restriction^b	Animal	Intercept (kg)		Slope (kg)		p value^c	R^2	Mean BW
			Estimate	SEM	Estimate	SEM
Katahdin	70	130	29.0	1.59	−0.056	0.0303	.208	.627	26.1
Katahdin	55	131	24.0	1.28	−0.014	0.0244	.635	.133	23.3
Katahdin	55	132	27.0	3.50	−0.071	0.0670	.398	.363	23.3
Katahdin	70	133	23.9	3.25	−0.007	0.0621	.926	.006	23.6
Katahdin	70	134	29.8	3.66	−0.049	0.0699	.587	.017	27.5
Katahdin	55	135	25.9	1.28	−0.030	0.0245	.341	.434	24.3
Katahdin	55	136	22.6	1.37	0.049	0.0262	.205	.632	25.1
Katahdin	70	138	27.0	1.34	−0.013	0.0254	.656	.119	26.3
Katahdin	70	140	29.8	0.74	−0.042	0.0141	.098	.813	27.7
Katahdin	55	141	23.7	2.61	−0.043	0.0500	.484	.266	21.4
Spanish	55	503	16.2	1.35	0.025	0.0257	.430	.324	17.5
Spanish	70	5031	16.1	2.95	0.075	0.0564	.316	.467	20.1
Spanish	70	5054	18.8	0.46	0.018	0.0087	.179	.675	19.8
Spanish	55	5056	20.1	2.55	−0.036	0.0487	.534	.219	18.2
Spanish	55	5060	17.8	2.07	0.021	0.0396	.655	.119	18.9
Spanish	70	5065	16.4	1.28	0.014	0.0244	.635	.133	17.1
Spanish	70	5066	20.5	1.98	−0.064	0.0379	.236	.584	17.2
Spanish	55	5068	16.5	3.68	0.018	0.0703	.824	.031	17.5
Spanish	55	5085	17.7	1.48	−0.013	0.0282	.699	.091	17.0
Spanish	70	5091	17.8	1.13	−0.002	0.0216	.939	.004	17.7

^aIntervals of 2 or 3 days in length.

^bFeeding levels were 55% and 70% of feed required for maintenance of each wether based on frequent small changes in feeding levels for constant BW in an earlier phase.

^cp values for difference from 0.

Table 6. BW and DMI required for maintenance (DMI_m) in week 8 of the feed restriction phase^a for treatments and individual KAT sheep and SPA goats.

Item	Animal^b	KAT sheep		SPA goats		SEM	p values
		55%	70%	55%	70%		Breed	Restriction	Interaction
BW (kg)	Mean	23.5	26.2	17.5	18.4	0.60	<.001	.014	.084
	131, 130, 503, 5031	23.3	26.1	17.5	20.1
	132, 133, 5056, 5054	23.3	23.6	18.2	19.8
	135, 134, 5060, 5065	24.3	27.5	18.9	17.1
	136, 138, 5068, 5066	25.1	26.3	17.5	17.2
	141, 140, 5085, 5091	21.4	27.7	17.0	17.2
DMI (g/day)	Mean	363	447	266	346	12.7	<.001	<.001	.880
	131, 130, 503, 5031	330	378	243	366
	132, 133, 5056, 5054	357	431	265	350
	135, 134, 5060, 5065	368	475	284	350
	136, 138, 5068, 5066	402	453	259	326
	141, 140, 5085, 5091	361	496	281	337
DMI (g/kg BW^0.75)	Mean^c	34.1	38.6	30.7	39.0	1.03	.188	<.001	.080
	131, 130, 503, 5031	31.1	32.8	28.3	38.6
	132, 133, 5056, 5054	33.7	40.3	30.0	37.3
	135, 134, 5060, 5065	33.6	39.5	31.4	41.5
	136, 138, 5068, 5066	35.9	39.0	30.3	38.7
	141, 140, 5085, 5091	36.2	41.2	33.5	39.1

^aFeeding levels were 55% and 70% of feed required for maintenance of each wether based on frequent small changes in feeding levels for constant BW in an earlier phase.

^bThe order of animals is that listed for breed × restriction level means.

^cInitial DMI relative to BW at the start of the restriction phase was 29.2, 37.2, 27.6, and 35.9 g/kg BW^0.75 for KAT-55%, KAT-70%, SPA-55%, and SPA-70%, respectively (SEM = 0.72).

Table 7. Correlation between DMI required for maintenance relative to BW^0.75 during maintenance and restriction phases based on the BW method.

Observations	n	Correlation coefficient	p value
All	20	.49	.028
KAT sheep	10	.21	.565
SPA goats	10	.69	.027
55% restriction level	10	.95	<.001
70% restriction level	10	.16	.669
KAT sheep, 55% restriction level	5	.89	.041
KAT sheep, 70% restriction level	5	−.06	.927
SPA goats, 55% restriction level	5	.96	.009
SPA goats, 70% restriction level	5	.85	.066

Note: Feeding levels were 55% and 70% of feed required for maintenance of each wether based on frequent small changes in feeding levels for constant BW in an earlier phase.

Table 8. Estimates of feed required for maintenance for KAT sheep and SPA goats with different levels of feed restriction and based on BW and HE determined from HR and the HE:HR ratio.

Item	Restriction^a				SE	Animal type		SEM	p value^b
	55%		70%
	BW	HR	BW	HR		KAT	SPA		A	R	M	A × R	A × M	R × M	A × R × M
DM (g/day)	315	385	396	426	11.3	435	326	8.0	<.001	<.001	<.001	.487	.425	.089	.590
DM (g/kg BW^0.75)	32.4^c	39.7^d	38.8^d	41.5^d	0.92	39.0	37.2	0.65	.061	<.001	<.001	.228	.715	.018	.381
ME (kJ/kg BW^0.75)	271^c	332^d	325^d	347^d	7.7	326	311	5.4	.061	<.001	<.001	.228	.715	.018	.381

Note: DM – dry matter; ME – metabolizable energy.

^aFeeding levels were 55% and 70% of feed required for maintenance of each wether based on frequent small changes in feeding levels for constant BW in an earlier phase.

^bA: animal type or breed; R: level of feed restriction treatment; M: method of estimation.

^c,dMeans in a row without a common superscript letter differ (p < 0.05).