Age and calving time affects production efficiency of beef cows and their calves

BITENCOURT, MARCIA F.; CERDÓTES, LILIANE; RESTLE, JOÃO; COSTA, PABLO T.; FERNANDES, TIAGO A.; FERREIRA, OTONIEL G. L.; SILVEIRA, DANIEL D.; VAZ, RICARDO Z.

doi:10.1590/0001-3765202020181058

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AGRARIAN SCIENCIES • An. Acad. Bras. Ciênc. 92 (suppl 1) • 2020 • https://doi.org/10.1590/0001-3765202020181058 copy

Age and calving time affects production efficiency of beef cows and their calves

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The aim of this study was to evaluate the influence of two sub-periods of the calving season and two cow maturity stages on the efficiency of beef cows and their calves. A total of 159 cow-calf pairs were divided by calving time (early or late) within the calving season and maturity stage (young or adult). Calves were weaned at 42 or 63 days after birth and evaluated until 210 days of age. Cows and calves had their development examined based on their weight and body condition score at calving, at weaning, and at 210 days. Reproductive performance was evaluated on the basis of time to become pregnant again. Milk yield was assessed by the direct method on three occasions spaced 21 days apart. Adult cows were heavier than young cows, at calving (398.5 vs 327.5 kg, respectively), weaning (397.3 vs 324.1 kg, respectively) at the end breeding season (424.1 vs 342.1 kg, respectively). Reproductive performance was influenced by calving time. Adult cows had higher pregnancy rates (83.75 and 69.17%, for early and for late calving, respectively) than young cows (57.03 and 35.01% for early and for late-calving, respectively). Calves from early-calving young cows weighed 158.8 kg at 210 days of age vs. 123.7 kg for those born from late-calving adult cows. However, late-calving cows produced 10.7% more milk than those that calved early in the season (227.0 vs 205.0 liters, respectively). Early calving associated with non-requirement of growth determine higher productivity efficiency in beef cows.

Key words
early weaning; pregnancy; milk yield; productivity

Endpoints	Early-calving		Late-calving
Endpoints	Young	Adult	Young		Adult
*Cows -Weights, kg*
At calving	322.6±10.2^b	397.4±7.6^a	331.5±10.4^b		399.6±5.2^a
At weaning	319.6±10.2^b	397.8±7.7^a	328.5±10.4^b		396.7±5.2^a
At end of breeding season	339.2±10.6^b	431.2±7.9^a	345.0±10.8^b		417.0±5.4^a
*Cows - Daily weight changes, kg day^-1*
From birth to weaning	-0.050±0.07^a	0.005±0.05^a	-0.048±0.07^a	-0.046±0.03^a
From calving to end of breeding season	0.114±0.04^b	0.227±0.03^a	0.124±0.04^b	0.155±0.02^ab
*Cows - Body condition score, points*
At calving	2.91±0.05^b	3.09±0.03^a	2.87±0.05^b			3.19±0.02^a
At weaning	2.89±0.05^b	3.13±0.04^a	2.84±0.05^b			3.22±0.02^a
At end of breeding season	3.06±0.06^b	3.38±0.04^a	2.99±0.06^b			3.22±0.03^a
*Calves - Weights, kg*
At birth	31.6±1.14^ab	33.3±0.86^a	29.1±1.16^b			32.5±0.58^a
At weaning	56.4±2.77^b	70.7±1.97^a	57.3±2.74^b			68.2±1.39^a
At 210 d of age	158.8±4.21^a	164.4±3.91^a	107.2±5.31^c			123.7±2.6^b
*Calves - Daily weight changes, kg*
From birth to weaning	0.390±0.04^a	0.590±0.02^a	0.450±0.04^a	0.560±0.02^a
From birth to 210 days of age	0.616±0.03^ab	0.639±0.02^a	0.467±0.03^c	0.577±0.01^b

	Early-calving		Late-calving
Endpoints	Young	Adult	Young	Adult
Pregnancy, %	57.03^C	83.75^A	35.01^D	69.17^B
Prod. efficiency at calving, kg¹	49.9±1.6^a	42.3±1.2^b	32.7±1.6^c	31.1±0.8^c
Prod. efficiency at 210 days, kg²	42.4±1.3^a	35.0±0.9^b	29.0±1.3^c	27.2±0.6^c
Calf production index, kg³	90.6±3.8^b	137.6±2.7^a	37.4±3.7^c	85.5±1.9^b
Cow production, kg	50.5±4.5^a	58.1±3.3^a	44.4±4.6^b	45.8±2.3^b
Calf, kg	117.7±4.3^a	99.9±3.1^a	77.7±4.4^b	74.6±2.2^b
Cow-calf pair production, kg⁴	168.2±6.2^a	158.0±4.6^a	122.1±6.3^b	120.4±3.2^b
Area required for production, ha⁵	1.08±0.03^c	1.32±0.02^a	1.01±0.03^d	1.22±0.02^b
Cow-calf pair production, kg ha^-1	155.7±6.3^a	119.7±5.1^b	120.9±6.5^b	98.7±4.1^c

	Early-calving		Late-calving
Endpoints	Young	Adult	Young	Adult
*Milk yield, kg*
21 days	4.18±0.36^ab	4.81±0.27^a	3.53±0.37^b	4.58±0.18^a
42 days	2.25±0.36^c	3.46±0.27^b	2.89±0.37^bc	4.48±0.18^a
63 days	1.53±0.44^c	3.37±0.32^ab	2.50±0.44^bc	3.71±0.24^a
Average milk yield	2.65±0.31^b	3.88±0.26^a	2.97±0.30^b	4.25±0.22^a
Total milk yield	167±7.3^b	244±6.8^a	187±6.5^b	268±6.9^a
*Lactation efficiency*
Calf weight gain	24.8±2.4^b	37.4±2.7^a	28.2±2.4^b	35.7±2.8^a
kg milk per kg calf¹	6.73±1.2^b	6.52±1.4^b	6.63±1.1^b	7.50±1.3^a
kg milk per kg calf²	14.9±0.33^a	15.3±0.32^a	15.0±0.33^a	13.3±0.31^a
*Milk components, %*
Protein, %	2.76±0.15^b	3.09±0.11^a	2.83±0.15^b	3.21±0.08^a
Fat, %	3.71±0.17^a	3.50±0.13^a	3.46±0.30^a	3.38±0.10^a
Lactose, %	4.84±0.08^a	4.97±0.05^a	4.83±0.07^a	4.86±0.05^a
Total solids, %	11.29±0.47^b	11.76±0.17^b	12.46±0.25^a	12.12±0.16^a

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[1] Correspondence to: Ricardo Zambarda Vaz E-mail: rzvaz@terra.com.br