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52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Estratégias de fornecimento de suplementos para vacas Nelore no terço final da gestação¹
Luciano Prímola de Melo², Felipe Henrique de Moura2, Marcos Rocha Manso2, Román Enrique Maza Ortega³,
Aline Gomes da Silva4, Lincoln da Silva Amorim5, Mário Fonseca Paulino6
1
Parte da tese de doutorado do quinto autor, projeto financiado pela FAPEMIG e CNPq.
Estudante de Graduação em Zootecnia, DZO/UFV, Viçosa – MG, Brasil. E-mail: [email protected]
³Estudante de Doutorado do Programa de Pós-Graduação em Zootecnia, DZO/ UFV, Viçosa – MG, Brasil.
4
Estudante de Doutorado em Zootecnia, DZO/ UFV e WCREC/UNL, North Platte – NE, USA, Bolsista CNPq (Março/2012-Julho/2014) e
Capes (Agosto/2014 até o presente). E-mail: [email protected]
5
CCAAB/UFRB, Cruz das Almas - BA, Brasil.
6
Professor do Departamento de Zootecnia, DZO/UFV, Viçosa – MG, Brasil.
2
Resumo: Um estudo com o objetivo de avaliar o efeito de três estratégias de fornecimento de suplemento para
vacas de corte durante o terço final da gestação foi realizado utilizando-se 35 vacas gestantes com 200 ± 15 dias de
gestação. Os animais foram distribuídos em delineamento inteiramente casualizado, com quatro tratamentos: um
grupo controle e três estratégias de fornecimento - 30 dias (30days; 3,0 kg/d de suplemento), 60 dias (60days; 1,5
kg/d de suplemento) ou 90 dias (90days; 1,0 kg/d de suplemento). Todos os tratamentos receberam a mesma
quantidade total de suplemento ao longo do experimento. Vacas que receberam 1,5 kg de suplemento nos últimos
60 d de gestação apresentaram maior peso corporal pre-parto, pós-parto e também maior peso corporal 31 d após o
parto (P<0,10). Crias nascidas de vacas na estratégia de fornecimento 60 dias obtiveram o menor peso corporal ao
nascimento (P=0,0477), mas aos 31 d após o nascimento não houve diferença entre os tratamentos (P>0,10). Houve
efeito quadrático sobre a porcentagem de vacas que concebem na primeira inseminação artificial em tempo fixo
(IATF; P=0,0870), vacas que receberam suplemento nos últimos 60 d de gestação apresentaram a maior taxa de
concepção após a primeira IATF, mas não houve diferença nas taxas de concepção ao final da estação de monta
(P>0,10). Conclui-se que 1,5 kg/d de suplemento durante os últimos 60 dias de gestação melhora o desempenho
reprodutivo da vaca na estação reprodutiva subsequente.
Palavras–chave: flushing, IATF, ovulação, taxa de gestação
Supplement delivery strategies for Nellore cows during the last third of gestation
Abstract: A study aiming to evaluate the effect of supplementation and 3 supplement delivery strategies for beef
cows on the last third of gestation was conducted using 35 cows with 200 ± 15 days of gestation. Animals were
assigned to a completely randomized design with 4 treatments, a control group, which received no supplement and
3 supplement delivery strategies: supplementation for the last 30 d of gestation (30days; 3.0 kg/d of supplement),
supplementation for the last 60 d of gestation (60days; 1.5 kg/d of supplement), or supplementation for the last 90
days of gestation (90days; 1.0 kg/d of supplement). All treatments received the same total amount of supplement.
Supplement was formulated to contain 25% of crude protein (CP). Cows that received 1.5 kg of supplement for the
last 60 d of gestation had higher pre-calving body weight (BW), post-calving BW and higher BW 31 d after calving
(P<0.10). Offspring from cows in the 60days strategy had the lowest birth BW (P=0.0477), but at 31 d after birth
there was no difference in calf BW between the treatments (P>0.10). There was a quadratic effect on the percentage
of cows that conceived to the first fixed time artificial insemination (FTAI; P=0.0870). The 60days strategy had the
highest pregnancy rate after the first FTAI, but there was no difference in the overall pregnancy rates (P>0.10). We
conclude that 1.5 kg of supplement fed for the last 60 d of gestation improves cow reproductive performance in the
following breeding season.
Keywords: flushing, FTAI, ovulation, pregnancy rate
Introduction
Among the factors affecting the reproductive performance of beef cattle, nutrition is perhaps the one that
has the highest impact (Santos & Amstalden, 1998). The use of supplementation to grazing animals is a practice
that can be adopted in pasture management strategy in Brazilian conditions to increase the supporting capacity of
the pastures and animal performance. In this context, finding the best strategy of supplementation is necessary to
reduce labor and consequently feeding cost. Therefore, we conducted a study to evaluate the effect of
supplementation and three supplement delivery strategies for pregnant beef cows on the last third of gestation.
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Página - 1 - de 3
52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Material and Methods
All animal care and handling procedures were approved by the Animal Care and Use Committee of the
Department of Animal Science of the Universidade Federal de Viçosa, Brazil. Thirty-five pregnant Nellore cows
with 491.88 ± 55 kg average BW and 200 ± 15 d of gestation were used. Pregnancy was confirmed before the
beginning of the experiment by rectal palpation. Cows were placed in an experimental area of Uruchloa decumbens
with free access to water and feeders.
The experimental treatments consisted of a control group - unlimited access to mineral and no concentrate
supplement was fed; and three different feeding strategies: 90days - cows received 1.0 kg of concentrate
supplement beginning 90 d prior calving; 60days - cows received 1.5 kg of concentrate supplement beginning 60 d
prior calving; and 30days - cows received 3.0 kg of concentrate supplement beginning 30 d prior calving. All
treatments received the same total amount of supplement throughout the experiment. Animals were assigned to a
completely randomized design with 4 treatments and 9 replicates for treatments control, 60days and 90days, and 8
replicates for treatment 30days.
The supplement was composed of corn and soybean meal, and formulated to contain approximately 25%
crude protein (CP). Cow body weight (BW) was recorded at the beginning of the experiment, one week before the
expected date of parturition (Pre-calving BW), 24 h after (Post-calving BW) and 31 d after parturition. Calf BW
was recorded at birth and 31 days after birth.
Cows were synchronized using the following protocol: on d 0 a controlled internal drug release (CIDR®)
device was inserted and injection of 2.0 mg of estradiol benzoate (RIC-BE®,Tecnopec) i.m. was performed, on d 7
the CIDR® was removed and cows received a 2 mL injection of cloprosterol sodium (Ciosin®, MSD Saúde animal),
on d 8 cows received 0.5 mL of estradiol cypionate i.m. (E.C.P.®, Zoetis-Pfizer), FTAI was preformed 46 to 52
hours following CIDR® removal (d 10). The same protocol was repeated in the cows that did not conceive in the
first FTAI. Pregnancy diagnosis was determined via trans-rectal ultrasonography 21 d after each FTAI. Overall
pregnancy rate was calculated by summing the number of cows that conceived in the first and second FTAI.
The response variables were analyzed using PROC MIXED and GLIMMIX in SAS 9.4. For cow
performance variables, cow initial body weight was used as a covariate in the model. Least square means were
compared by orthogonal contrasts at α=0.10.
Results and Discussion
The results for cow and calf performance and reproductive performance are presented in Table 1.
Table 1. Means, standard error (SE) and indicatives of significance for Cow and Calf Performance
and Reproductive Performance
Treatment
P-valuea
Item
SE
Control 30days 60days 90days
S
L
Q
Cow and Calf Body Weights (kg)
Initial cow BW
494.1
484.4
492.2
496.0
20.36
0.8851
0.6806
0.9323
Pre-calving cow BW
530.0
516.2
538.9
7.22
0.9236
0.0413
0.1530
Post-calving cow BW
474.6
472.9
500.2
537.3
477.1
8.39
0.3463
0.7113
0.0172
Calf birth BW
36.4
33.5
30.1
35.6
1.83
0.1107
0.4335
0.0477
Cow BW 31d after calving
473.1
474.4
512.6
491.2
8.83
0.0492
0.1835
0.0058
Calf BW 31d after calving
62.5
60.1
61.4
64.5
Cow Reproductive Performance (%)
1.95
0.8006
0.1139
0.7144
Cows cycling 31d after calving
0.00
37.50
33.70
22.20
0.80
0.9776
0.4990
0.8337
Pregnancy rate (1º insemination)
44.44
37.50
66.67
22.22
0.80
0.8680
0.4990
0.0870
Overall pregnancy rate
88.89
75.00
88.89
55.56
1.06
0.4259 0.4137 0.2403
a
/S=effect of supplementation, supplemented treatments compared to the control; L and Q = effects of linear and
quadratic order of strategy of supplementation (30, 60 or 90 d).
There was a positive linear effect of supplement strategy on pre-calving cow BW (P=0.0413) and a quadratic
effect on post-calving cow BW and cow BW 31 days after parturition (P =0.0172 and P=0.0477, respectively).
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52a Reunião Anual da Sociedade Brasileira de
Zootecnia
Zootecnia: Otimizando Recursos e Potencialidades
Belo Horizonte – MG, 19 a 23 de Julho de 2015
Cows that received 1.5 kg of supplement for the last 60 d of gestation had higher pre-calving BW, post-calving BW
and also higher BW 31 d after calving.
Although 60days cows had higher BW at parturition, their offspring had the lowest birth BW (quadratic
effect; P=0.0477). At 31 d after birth there was no difference between the treatments (P>0.10) for calf BW.
Despite the fact there was no difference in the percentage of cows cycling 31 d after parturition (P>0.10), a
quadratic effect on the percentage of cows that conceive in the first FTAI was observed (P=0.0870), treatment
60days had the highest pregnancy rate after the first FTAI, but there was no difference in the overall pregnancy
rates (P>0.10). Cows that conceive early, calve early and have better opportunity to start reproductive cycles in time
to conceive in next breading season. Calving date also affects the value of offspring, demonstrating the importance
of strategies to improve conception rates at the beginning of breading season.
Cushman et al. (2013) and Funston et al. (2012) reported that heifer calves born early tend to conceive early
in their first breading season and remain in the herd. Cow calving date can also impact male offspring performance;
steer calves born earlier in the calving season have greater weaning BW, hot carcass weight, and marbling scores
(Funston et al., 2012). In this way, increasing early calving by early conception may increase progeny value at
weaning, enhance carcass value of the steers and increase heifer’s pregnancy rate in their first breading season.
Conclusions
We conclude that 1.5 kg of supplement for the last 60 days of gestation improves cow reproductive
performance in the following breeding season.
Acknowledgements
The authors thank to Fapemig and CNPq for project financial support and CNPq and Capes for the
scholarships provided.
References
Cushman, R. A.; Kill, L. K.; Funston, R. N.; Mousel, E. M. and Perry, G. A. 2013. Heifer calving date positively
influences calf weaning weights through six parturitions. Journal of Animal Science, 91(9): 4486-4491.
Funston, R. N.; Musgrave, J. A.; Meyer, T.L. and Larson, D. M. 2012. Effect of calving distribution on beef cattle
progeny performance. Journal of Animal Science, 90: 5118–5121.
Santos, J. E. P. and Amstalden, M. 1998. Effects of nutrition on bovine reproduction. Arquivos da Faculdade de
Veterinária da UFRGS, 26: 19-89.
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