Effects of dam prepartum supplement level on performance and reproduction of heifer progeny

Figures & data

Table 1. Composition (DM basis) of diet fed to heifers during feed efficiency evaluation.

	Inclusion, % DM
Item	year 1	year 2(d0–d42)	year 2(d43–d70)
Ingredient, %
Grass hay	100.0
Alfalfa hay		42.0	39.0
Fescue hay			28.0
Cornstalk baleage		24.5
Soybean hulls, pelleted		33.5	33.0
Analysed nutrient content, %
CP	13.5	14.1	12.8
NDF	63.4	55.1	60.2
ADF	53.7	38.9	43.4
Crude fat	1.3	1.3	1.4
Calculated energy content
TDN^a	44.9	52.0	47.4

a Total digestible nutrients was back-calculated from CP and ADF using TDN =81.38 + (CP * 0.36) − (ADF * 0.77) for year 1 hay and TDN =90.82 + (CP * 0.0353) − (ADF * 1.01).

Table 2. Effect of dam prepartum supplement level on heifer progeny growth and performance.

	Supplement^a				p value^b
Item	NS	LS	HS	SE	year	SUP
n, dam pasture	6	6	6	–
Weaning BW, kg	177	177	178	5.5	<.01	.99
Initial BW^c, kg	253	253	256	5.6	<.01	.89
Final BW^c, kg	300	304	307	6.5	<.01	.76
DMI, kg	7.9	8.1	8.2	0.18	<.01	.51
ADG, kg/d	0.66	0.72	0.71	0.023	<.01	.14
G:F	0.190	0.203	0.195	0.004	<.01	.10
RFI	−0.050	0.002	0.079	0.088	.76	.59

a Supplement level: NS = no supplement; LS = low supplement, 2.16 kg·cow ^− 1·d ^− 1; HS = high supplement, 8.61 kg·cow ^− 1·d ^− 1.

b SUP = supplement level; SUP × year ≥0.26.

c Start of feed efficiency test; 305 ± 11 d of age; End of feed efficiency test =375 ± 11 d of age.

Table 3. Effects of dam prepartum supplement level on heifer progeny performance.

	Supplement^a				p value^b
Item	NS	LS	HS	SE^c	year	SUP
n, dam pasture	6	6	6	–
Breeding BW, kg	315	314	322	5.5	<.01	.60
Percent mature BW at breeding^d	51	51	52	0.9	<.01	.61
Breeding BCS	5.0	5.0	5.0	0.07	<.01	.93
Pregnancy check BW, kg	337	337	345	6.1	.08	.62
AI conception rate^e, %	31	39	43	0.08	.20	.54
Overall pregnancy rate^f, %	82	81	92	0.06	.67	.18
Calving rate^g, %	68	67	75	0.08	.79	.66

a Dam supplement level: NS = no supplement; LS = low supplement, 2.16 kg·cow ^− 1·d ^− 1; HS = high supplement, 8.61 kg·cow⁻¹·d ⁻¹.

b SUP = supplement level. SUP × year ≥0.39.

c Standard error for AI conception rate, overall pregnancy rate, and calving rate are in transformed units.

d Estimated percent of mature weight when heifers were inseminated. Calculation based on average initial BW of dams.

e Number of confirmed pregnant heifers at 58 ± 3 d post-AI/number of heifers inseminated.

f Number of confirmed pregnant heifers at 45 ± 4 d post-bull removal/number of total heifers inseminated.

g Number of total heifers with a recorded calf/number of heifers inseminated.

Table 4. Effect of dam prepartum supplement level on heifer progeny’s first calf performance.

	Supplement^a				p value^b
Item	NS	LS	HS	SE^c	year	SUP
n, dam pasture	6	6	6	–
Calving date^d	253	252	249	3.7	.35	.72
Calved unassisted, %	97	97	95	0.03	.18	.43
Calf birth BW, kg	29	31	30	0.9	.10	.32
Milk production, kg^e	5.1	5.7	5.2	0.34	.01	.48
Calf BW at WSW, kg^f	86	92	89	2.4	.15	.24

a Dam supplement level: NS = no supplement; LS = low supplement, 2.16 kg·cow⁻¹·d⁻¹; HS = high supplement, 8.61 kg·cow⁻¹·d⁻¹.

b SUP = supplement level; SUP × year ≥0.27.

c Standard error for percent calving unassisted are in transformed units.

d Unique combination of d and month. For example, 253 = September 10th.

e 73 ± 16 d post-partum.

f Calf BW collected at weigh-suckle-weigh; 73 ± 16 d of age.