RESUMO

The raising of pastures is an alternative to improve biological efficiency in finishing beef cattle. For this, it is important to know the variables performance on different pastures. In this work were evaluated data from 1071, castrated male bovine between three to fi ve years of age. The animals before finishing were recreated in native field, and after were finished on cultivated pastures of ryegrass and millet. In the winters of 2010 and 2011 were fi nished 710 animals and in the summers of 2010/11 and 2011/12 were finished 361 animals. To evaluate the performance of the animals was determined the average daily weight gain (DWG), average weight gain (WG) and age animal (AA). The variables used were initial average weight (IAW), average final weight (AFW) and average time of permanence (ATP) in pastures. The DWG and WG were respectively of 1,22 kg/day and 87,3 kg in ryegrass pastures and 1,43 kg/day and 55,5 kg in the pastures of millet. The AA not influences the DWG and WG. The cultivated pastures represent an alternative to improve animal performance in finishing beef cattle with different ages throughout the year.

O cultivo de pastagens representa uma alternativa para melhorar a efi ciência biológica na terminação de bovinos de corte. Para isso, é importante conhecer as variáveis no desempenho dos animais sobre diferentes pastagens. No presente trabalho, avaliaram-se dados de 1071 bovinos, machos, castrados, entre três a cinco anos de idade. Os animais, recriados em campo nativo, foram terminados sobre pastagens cultivadas de azevém e milheto. Nos invernos de 2010 e 2011 foram terminados 710 animais em pastagens de azevém e nos verões de 2010/11 e 2011/12 foram terminados 361 animais em pastagens de milheto. Para avaliar o desempenho animal foi determinado o ganho médio diário de peso (GMD), o ganho médio de peso (GP) e a idade dos animais (IA). As variáveis usadas foram peso médio inicial (PMI), peso médio fi nal (PMF) e tempo médio de permanência (TMP) nas pastagens. O GMD e o GP foram respectivamente de 1,22 kg/dia e 87,3 kg nas pastagens de azevém e 1,43 kg/dia e 55,5 kg nas pastagens de milheto. A IA média dos animais terminados em azevém no inverno de 2010 foi de quatro anos e no inverno de 2011 de três anos, dos animais terminados em milheto foi de três anos e meio em ambos os ciclos. O GMD e o GP foram significativamente diferentes (P 0,01) para as pastagens de azevém e milheto. A IA não exerceu influência no GMD e no GP. O cultivo de pastagens representa uma alternativa para

RESUMO

The raising of pastures is an alternative to improve biological efficiency in finishing beef cattle. For this, it is important to know the variables performance on different pastures. In this work were evaluated data from 1071, castrated male bovine between three to fi ve years of age. The animals before finishing were recreated in native field, and after were finished on cultivated pastures of ryegrass and millet. In the winters of 2010 and 2011 were fi nished 710 animals and in the summers of 2010/11 and 2011/12 were finished 361 animals. To evaluate the performance of the animals was determined the average daily weight gain (DWG), average weight gain (WG) and age animal (AA). The variables used were initial average weight (IAW), average final weight (AFW) and average time of permanence (ATP) in pastures. The DWG and WG were respectively of 1,22 kg/day and 87,3 kg in ryegrass pastures and 1,43 kg/day and 55,5 kg in the pastures of millet. The AA not influences the DWG and WG. The cultivated pastures represent an alternative to improve animal performance in finishing beef cattle with different ages throughout the year.

O cultivo de pastagens representa uma alternativa para melhorar a efi ciência biológica na terminação de bovinos de corte. Para isso, é importante conhecer as variáveis no desempenho dos animais sobre diferentes pastagens. No presente trabalho, avaliaram-se dados de 1071 bovinos, machos, castrados, entre três a cinco anos de idade. Os animais, recriados em campo nativo, foram terminados sobre pastagens cultivadas de azevém e milheto. Nos invernos de 2010 e 2011 foram terminados 710 animais em pastagens de azevém e nos verões de 2010/11 e 2011/12 foram terminados 361 animais em pastagens de milheto. Para avaliar o desempenho animal foi determinado o ganho médio diário de peso (GMD), o ganho médio de peso (GP) e a idade dos animais (IA). As variáveis usadas foram peso médio inicial (PMI), peso médio fi nal (PMF) e tempo médio de permanência (TMP) nas pastagens. O GMD e o GP foram respectivamente de 1,22 kg/dia e 87,3 kg nas pastagens de azevém e 1,43 kg/dia e 55,5 kg nas pastagens de milheto. A IA média dos animais terminados em azevém no inverno de 2010 foi de quatro anos e no inverno de 2011 de três anos, dos animais terminados em milheto foi de três anos e meio em ambos os ciclos. O GMD e o GP foram significativamente diferentes (P 0,01) para as pastagens de azevém e milheto. A IA não exerceu influência no GMD e no GP. O cultivo de pastagens representa uma alternativa para

RESUMO

Background: The success of fixed-time artifi cial insemination (FTAI) is linked to several factors that affect pregnancy rates. The use of different hormones, estrus expression and body condition score (BCS) are variables that can infl uence the results of the technique. The increased production of calves provides greater amount of steers to slaughter. The productive intensifi cation of the beef cows breeding depends on factors related to reproductive technique used and the physiological conditioning of animals. The objective of this study was to evaluate the effect of the application of GnRH, estrus manifestation, re-use of progesterone intravaginal devices and BCS on pregnancy rates of cows subjected to FTAI.Materials, Methods & Results: Were analyzed the effects of GnRH injection and re-use of intravaginal device, estrus manifestation and body condition score (BCS) on reproductive performance of 222 Montana beef cows subjected to fixedtime artifi cial insemination (FTAI). The FTAI protocol was based on the placement of intravaginal progesterone device (1st, 2nd or 3rd use) and application of estradiol benzoate (E.B.) (2 mg) on day 0. On day 8 was applied sodium cloprostenol (500 µg), removed the intravaginal device and performed the separation of calves. On day 9 was applied E.B. (1 mg) and started the observation of estrus in the morning, afternoon and morning of day 10

Background: The success of fixed-time artifi cial insemination (FTAI) is linked to several factors that affect pregnancy rates. The use of different hormones, estrus expression and body condition score (BCS) are variables that can infl uence the results of the technique. The increased production of calves provides greater amount of steers to slaughter. The productive intensifi cation of the beef cows breeding depends on factors related to reproductive technique used and the physiological conditioning of animals. The objective of this study was to evaluate the effect of the application of GnRH, estrus manifestation, re-use of progesterone intravaginal devices and BCS on pregnancy rates of cows subjected to FTAI.Materials, Methods & Results: Were analyzed the effects of GnRH injection and re-use of intravaginal device, estrus manifestation and body condition score (BCS) on reproductive performance of 222 Montana beef cows subjected to fixedtime artifi cial insemination (FTAI). The FTAI protocol was based on the placement of intravaginal progesterone device (1st, 2nd or 3rd use) and application of estradiol benzoate (E.B.) (2 mg) on day 0. On day 8 was applied sodium cloprostenol (500 µg), removed the intravaginal device and performed the separation of calves. On day 9 was applied E.B. (1 mg) and started the observation of estrus in the morning, afternoon and morning of day 10

RESUMO

Background: The success of fixed-time artificial insemination (FTAI) is linked to several factors that affect pregnancy rates. The use of different hormones, estrus expression and body condition score (BCS) are variables that can influence the results of the technique. The increased production of calves provides greater amount of steers to slaughter. The productive intensification of the beef cows breeding depends on factors related to reproductive technique used and the physiological conditioning of animals. The objective of this study was to evaluate the effect of the application of GnRH, estrus manifestation, re-use of progesterone intravaginal devices and BCS on pregnancy rates of cows subjected to FTAI. Materials, Methods & Results: Were analyzed the effects of GnRH injection and re-use of intravaginal device, estrus manifestation and body condition score (BCS) on reproductive performance of 222 Montana beef cows subjected to fixedtime artificial insemination (FTAI). The FTAI protocol was based on the placement of intravaginal progesterone device (1st, 2nd or 3rd use) and application of estradiol benzoate (E.B.) (2 mg) on day 0. On day 8 was applied sodium cloprostenol (500 µg), removed the intravaginal device and performed the separation of calves. On day 9 was applied E.B. (1 mg) and started the observation of estrus in the morning, afternoon and morning of day 10. On the afternoon of day 10 was realized the insemination, part of the animals showed estrus received buserelin acetate (GnRH) (100µg); the same was proceeded with the animals without estrus. After FTAI the calves returned to cows. Thus, it was formed four groups: Without-Estrus/Without-GnRH; Without-Estrus/With-GnRH; With-Estrus/Without-GnRH; With-Estrus/With-GnRH. The evaluation alone of application of GnRH (with and without) and estrus manifestation (with and without) had no effect on pregnancy rates to FTAI and pregnancy final (P > 0.05). The evaluation of the interaction between GnRH and estrus had no effect on the FTAI pregnancy (P > 0.05): cows Without-Estrus/Without-GnRH did not differ those with GnRH, 33.3% and 48.4% respectively; cows With-Estrus/Without-GnRH did not differ those with GnRH, 53.2% and 53.8% respectively. Intravaginal device 1st, 2nd and 3rd use did not influence pregnancy rates to FTAI and final pregnancy, 50.0%, 57.7%, 41.7% and 91.7%, 88.5%, 93 8% respectively (P > 0.05). The BCS influenced the pregnancy rate to FTAI and final pregnancy, animals with BCS ≥ 3.0 had a higher pregnancy rate to FTAI and animals with BCS ≥ 2.5 had a higher pregnancy to final pregnancy (P < 0.05). The BCS also influenced the estrus manifestation, animals with BCS ≥ 2.5 had higher rates of estrus (P < 0.05). The intravaginal device 1st use promoted greater estrus manifestation in relation to the 2nd and 3rd use (P < 0.05). Discussion: The pregnancy rates did not have the effect of application of GnRH. Some studies report that effect of GnRH is related to estrus phase of the cow. Although 11 percentage points above to cows with estrus, the manifestation estrus did not influence the pregnancy and also did not interact with GnRH. However, it is reported that estrus before at insemination may be conducive to conception. The intravaginal devices used did not influence the pregnancy rates, showing that it is possible re-use them. The results showed at importance of BCS to pregnancy, studies report that cows with low BCS have difficulty to pregnant at FTAI and clean-up bulls. The estrus manifestation was influenced by the BCS and the intravaginal device used.

Assuntos

RESUMO

Background: The success of fixed-time artifi cial insemination (FTAI) is linked to several factors that affect pregnancy rates. The use of different hormones, estrus expression and body condition score (BCS) are variables that can infl uence the results of the technique. The increased production of calves provides greater amount of steers to slaughter. The productive intensifi cation of the beef cows breeding depends on factors related to reproductive technique used and the physiological conditioning of animals. The objective of this study was to evaluate the effect of the application of GnRH, estrus manifestation, re-use of progesterone intravaginal devices and BCS on pregnancy rates of cows subjected to FTAI.Materials, Methods & Results: Were analyzed the effects of GnRH injection and re-use of intravaginal device, estrus manifestation and body condition score (BCS) on reproductive performance of 222 Montana beef cows subjected to fixedtime artifi cial insemination (FTAI). The FTAI protocol was based on the placement of intravaginal progesterone device (1st, 2nd or 3rd use) and application of estradiol benzoate (E.B.) (2 mg) on day 0. On day 8 was applied sodium cloprostenol (500 µg), removed the intravaginal device and performed the separation of calves. On day 9 was applied E.B. (1 mg) and started the observation of estrus in the morning, afternoon and morning of day 10

Background: The success of fixed-time artifi cial insemination (FTAI) is linked to several factors that affect pregnancy rates. The use of different hormones, estrus expression and body condition score (BCS) are variables that can infl uence the results of the technique. The increased production of calves provides greater amount of steers to slaughter. The productive intensifi cation of the beef cows breeding depends on factors related to reproductive technique used and the physiological conditioning of animals. The objective of this study was to evaluate the effect of the application of GnRH, estrus manifestation, re-use of progesterone intravaginal devices and BCS on pregnancy rates of cows subjected to FTAI.Materials, Methods & Results: Were analyzed the effects of GnRH injection and re-use of intravaginal device, estrus manifestation and body condition score (BCS) on reproductive performance of 222 Montana beef cows subjected to fixedtime artifi cial insemination (FTAI). The FTAI protocol was based on the placement of intravaginal progesterone device (1st, 2nd or 3rd use) and application of estradiol benzoate (E.B.) (2 mg) on day 0. On day 8 was applied sodium cloprostenol (500 µg), removed the intravaginal device and performed the separation of calves. On day 9 was applied E.B. (1 mg) and started the observation of estrus in the morning, afternoon and morning of day 10