Eficiência biológica de vacas de dois grupos genéticos amamentando bezerros puros ou F1, mantidas em diferentes condições de alimentação

Restle, João; Pacheco, Paulo Santana; Pádua, João Teodoro; Rocha, Marta Gomes da; Vaz, Ricardo Zambarda; Eifert, Eduardo da Costa; Moletta, José Luiz; Freitas, Aline Kellermann de

doi:10.1590/s1516-35982004000700021

Cited by 6 publications

(7 citation statements)

References 19 publications

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“…Neste estudo, são abordados e discutidos os resultados referentes às características de eficiência biológica relativas às diferentes taxas de ganho de peso das vacas quando bezerras. A discussão referente aos tipos de pastagem foi abordada com maior amplitude em trabalho complementar (Restle et al, 2004).…”

Section: Resultsunclassified

Influência das taxas de ganho de peso pré-desmame das vacas e do tipo de pastagem no período pós-parto sobre a eficiência biológica de vacas e de bezerros de corte

et al. 2007

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Objetivou-se com este estudo avaliar a influência de duas taxas de ganho de peso de bezerras (baixa: 340 ± 32 g/dia ou moderada: 490 ± 29 g/dia) do nascimento aos 7 meses de idade e do tipo de pastagem no período pós-parto, quando vacas, sobre sua eficiência biológica e de seus bezerros até o desmame (aos 217 dias). Quando vacas e após o parto, os animais foram mantidos em pastagem nativa (PN) ou em pastagem cultivada (PC). Durante a lactação, vacas com baixa taxa de ganho de peso pré-desmame apresentaram maior produção de leite. Houve similaridade entre as taxas de ganho de peso baixa e moderada para a conversão de litros de leite (7,32 e 6,44 L/kg, respectivamente) e de kg de MS de leite produzido pelas vacas (1,00 e 0,86 kg/kg, respectivamente) em kg de ganho de peso dos bezerros; a exigência total de energia líquida para mantença (mantença + gestação + produção de leite) (TOTELm) (2.733,7 e 2.316,7 Mcal, respectivamente); TOTELm por kg de bezerro desmamado (14,7 e 14,7 Mcal/kg, respectivamente); e kg de bezerro desmamado por 100 kg de vaca ao desmame (42,0 e 38,7 kg/100 kg, respectivamente). No entanto, vacas com baixa taxa de ganho de peso pré-desmame desmamaram mais kg de bezerros por unidade de peso metabólico da vaca ao desmame (1,89 vs 1,73 kg/g).

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Section: Resultsunclassified

Influência das taxas de ganho de peso pré-desmame das vacas e do tipo de pastagem no período pós-parto sobre a eficiência biológica de vacas e de bezerros de corte

et al. 2007

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“…However, upon evaluating herd efficiency, reproductive rates must be taken into account [12,33]. Therefore, higher milk production cows tend to wean heavier calves [30] and even they were more efficient at weaning. Nevertheless, the higher level of milk production can negatively affect the cow body condition score and, consequently, the reproductive efficiency in a beef cattle range system [2,18,35,36].…”

Section: Discussionmentioning

confidence: 99%

Performance Efficiency of Pasture-raised Primiparous Beef Cows of Three Different Biotypes and Two Milk Production Levels

Lemes

Pimentel

Vaz

et al. 2017

Acta Scientiae. Vet.

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Background: Productivity and efficiency of beef production systems should be estimated based on cow size, calf growth rate and cow reproduction rate, which are critical factors for the evaluation of production characteristics of beef cattle of different biological types. One of the ways to measure beef cow productivity is based on the ratio of calf weaning weight to cow weight. The purpose of this study was to evaluate the performance and reproductive efficiency of primiparous beef cows of three different biotypes and two milk production levels, from calving to weaning, in pasture-raised beef systems. Materials, Methods & Results: Forty-two primiparous Angus cows were classified according to body weight at calving, as follows: Heavy (431 kg); Medium (388 kg); and Light (348 kg). Cow efficiency as a function of biotype was evaluated at two different moments: calving and weaning, based on the ratio of calf weight to cow weight*100 (in kilograms). Calf production efficiency was determined based on the ratio of calf weaning weight (CWW) to cow pregnancy rate (PR), resulting in the calf production index = kg of weaning calves per cow (CWW*PR/100). The experimental design was a completely randomized factorial 3 x 2 x 2 design (three biotypes x two calf sexes x two milk production levels). The results were subjected to ANOVA and F-test. The Light and Medium cow groups produced more (P < 0.05) kilograms of calf per kilogram of cow (16.0 and 15.1 kg, respectively) than the Heavy group (14.0 kg). Light cows showed lower (P < 0.05) milk production and, as a result, lighter (P < 0.05) calves at weaning (151.9 ± 4.3 kg) than Medium and Heavy groups, 166.0 ± 3.7; 166.5 ± 4.0 kg, respectively. At beginning of the breeding season, cows of the Lower milk production group were on average 27.49 kg heavier than cows in the Higher milk production group. There was an interaction (P < 0.05) between total milk production and calf sex on characteristics of performance in calves and performance efficiencies of the system. Light and Medium cows showed 51 and 25 kg total weight gain from calving to weaning, corresponding to 14.7 and 6.4% of body weight, respectively. The Heavy group, however, showed a 3 kg loss (0.5% of body weight) during the same period. Discussion: A higher growth rate was observed in the pre-weaning period of the calves of heavy cows; as a result, these calves were heavier at weaning. To achieve this result, heavier cows may compensate this higher nutritional requirement using body reserves. This biological adjustment may not be economically efficient, since the subsequent reproduction of these cows could be impaired by increases in milk production. Therefore, the target cow in a pasture-raised beef system is one whose low nutritional requirements enable her to produce milk, resulting in heavier calves, and whose physiological conditions enable her to conceive again during the breed season. Light cows can be considered an efficient group, since their pregnancy rate enabled them to create a positive difference for the group, notwithstanding their lower milk production and lighter calves (P < 0.05) at weaning. This tendency is expected, since increased growth rates are associated with a decrease in puberty and early finishing age. It is essential to select animals according to their efficiency in order to reduce the cow’s requirements, since this favors the increased productivity of cows of lower maintenance cost in relation to their body weight, leading to higher biological and economic efficiency in the beef production system. In conclusion, because of their lower nutritional requirements, cows of small and moderate biotypes and lower total milk production are more efficient than cows of larger biotypes and higher milk production in pasture-raised beef systems.

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“…Even with a smaller size and subjected to the same feeding schedules as the other weight categories, the lower milk production of light cows did not influence the production of calves because the smaller frame of the animals was correlated with a lower milk consumption for conversion into kilograms of body weight. For Restle et al (2004), genetic groups have less of an influence than food systems. The authors did not observe differences between Charolais and Nellore cows grazing on natural or cultivated pastures.…”

Section: Resultsmentioning

confidence: 99%

“…The quality and quantity of milk produced may be directly or indirectly influenced by collection methods (RODRIGUES et al, 2014), lactation period, production levels LEMES et al, 2017), and variations in the source of nutrients for the cow-calf pair (RESTLE et al, 2004). However, studies show that calf development and calf weight at weaning are a direct result of the milk production of their mothers (RODRIGUES et al, 2014).…”

Section: Resultsmentioning

confidence: 99%

Biological efficiency of Charolais beef cows of different body sizes

Farias

Cerdótes

Vaz

et al. 2018

SCA

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This study aimed to evaluate the production, reproductive performance, and productive efficiency of predominantly Charolais cows and their calves (Straightbred, ¾ C, ¼ N) according to body size at calving. Sixty-three cow-calf pairs were used and classified into three weight groups: Light (331.3±5.8 kg), Moderate (385.9±5.3 kg), and Heavy (424.4±6.2 kg). The classes were formed using half standard deviations above or below the average weight of the cows at calving. For each pair, the body weight was evaluated at calving, at weaning (63 days), at the beginning and at end of the reproductive period, and at 9 months for the calves. Pregnancy rates were similar (P > 0.05) between weight groups. The calves did not differ (P > 0.05) in terms of body weight and weight gain from calving until pregnancy diagnosis (210 days). The heavy cows had greater weight variations from 210 days to 270 days than the light cows. The calf production rate (kg calf/cow kept in herds) did not differ between weight groups. However, in relation to the weight of the cows at 210 days, light cows were 11.28% and 13.02% more productive (P < 0.05), than moderate and heavy cows, respectively. Light cows were more efficient than the other classes of cows at calving and at 210 days old. Our simulations showed that there were more kilograms for sale in herds of light cows (53.085 kg) than moderate and heavy cows (52.310 and 52.870 kg, respectively), while maintaining the structures of the herd constant. The size of the Charolais cow did not influence the weight of calves from calving until 7 months of age or their reproductive performance provided they were weaned early. The need for space for the maintenance of the cow-calf pair increased as the weight of the cows increased. In herds with smaller cows, higher numbers and a higher production of weight for sale are observed than in herds with moderate and heavy cows. Light cows were the most efficient at calving and during pregnancy diagnosis at 210 days.

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Eficiência biológica de vacas de dois grupos genéticos amamentando bezerros puros ou F1, mantidas em diferentes condições de alimentação

Cited by 6 publications

References 19 publications

Influência das taxas de ganho de peso pré-desmame das vacas e do tipo de pastagem no período pós-parto sobre a eficiência biológica de vacas e de bezerros de corte

Influência das taxas de ganho de peso pré-desmame das vacas e do tipo de pastagem no período pós-parto sobre a eficiência biológica de vacas e de bezerros de corte

Performance Efficiency of Pasture-raised Primiparous Beef Cows of Three Different Biotypes and Two Milk Production Levels

Biological efficiency of Charolais beef cows of different body sizes

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