Resumo
Background: The need for high production has increased considerably in the dairy industry. On the other hand, a fertility decline has been observed in cows with best potential for milk production. Therefore, calving intervals of around 12 months have been sought, which leaves a very short period of time for the cows to be inseminated and to become pregnant. If the conception is delayed, the reproduction inefficiency can reduce milk production, causing economic problems. The calving-conception interval (CCI) depends on multiple factors such as voluntary waiting period, insemination technique, birth season, herd size and parity. Negative effects of stress caused by heat on the fertility of lactating dairy cows have been observed. An increase in body temperature decreased the probability of conception at 28 days as the number of postpartum days increased. It is known that cows with larger calving-conception intervals have more health problems. Also, they have a greater chance of being discarded, since long CCI result in longer periods with no milk production and, therefore, expenditures with unproductive cows. Moreover, an increase in the CCI from 90 to 300 days doubled the chance of discard or peripartum death in dairy matrix. This study aimed to analyze the effect of two variables: the calving - first IA interval and on the CCI of crossbred dairy cows: duration of previous calving interval and calving season. Materials, Methods & Results: Data were collected at a property located in the state of Goiás, Brazil, between 2009 and 2010, for a herd of 71 crossbred cows with an average production of 1,400 kg of milk per day. Cows were artificially inseminated and pregnancy diagnosis was performed monthly using ultrasonography (Mindray DP3.300® VET). The previous calving interval was evaluated in three subdivisions: 1 (300 365 days) 2 (366 500 days) 3 (above 500 days) and birth season was classified as spring-summer and autumn-winter. The calving-first IA interval and the CCI were analyzed by ANOVA in MINITAB. The effects of previous calving interval and birth season were included in the model. There was no effect of duration of either previous calving interval or calving season on the calving - first IA interval, but the birth season variable affected the CCI. Cows that calved in autumn/winter had a lower CCI when compared with calving in spring/summer (80.17 d. vs. 118.50 d). Discussion: In hot summers the conception rate is lower among cows that deliver during summer and spring when compared with those that deliver during autumn and winter [4]. Other authors have shown that conception during summer was, respectively, 25 to 30% and 36% lower than during winter. Although the length of the previous birth interval did not influence the calving-conception interval, herds with average CPI greater than 13.9 months had a 1.78 times higher risk of death than herds with average CPI smaller than 13 months. In addition, the risk of cows being discarded increased due to a decline in milk production for CCI greater than 15 months. This is particularly an issue for crossbred herds due to their low lactation persistence. The CCI was significantly influenced by the calving season and it was also influenced the CCI in Gir cows in the Northeast Brazil that had calving interval of 460 +9.4 days when they that calved in spring/summer and 430.8 +9.5 days when they calved in autumn/winter. The effect of the calving season on the service period has been explained as a result of poorer feeding conditions at certain times of the year for purebreds. Other authors contradict these results, but they investigated Nelore cows, showing the adaptation of this breed in subtropical climates.
Assuntos
Animais , Feminino , Gravidez , Bovinos , Estações do Ano , Prenhez , Bovinos , Inseminação Artificial/veterináriaResumo
Background: The need for high production has increased considerably in the dairy industry. On the other hand, a fertility decline has been observed in cows with best potential for milk production. Therefore, calving intervals of around 12 months have been sought, which leaves a very short period of time for the cows to be inseminated and to become pregnant. If the conception is delayed, the reproduction inefficiency can reduce milk production, causing economic problems. The calving-conception interval (CCI) depends on multiple factors such as voluntary waiting period, insemination technique, birth season, herd size and parity. Negative effects of stress caused by heat on the fertility of lactating dairy cows have been observed. An increase in body temperature decreased the probability of conception at 28 days as the number of postpartum days increased. It is known that cows with larger calving-conception intervals have more health problems. Also, they have a greater chance of being discarded, since long CCI result in longer periods with no milk production and, therefore, expenditures with unproductive cows. Moreover, an increase in the CCI from 90 to 300 days doubled the chance of discard or peripartum death in dairy matrix. This study aimed to analyze the effect of two variables: the calving - first IA interval and on the CCI of crossbred dairy cows: duration of previous calvi
Background: The need for high production has increased considerably in the dairy industry. On the other hand, a fertility decline has been observed in cows with best potential for milk production. Therefore, calving intervals of around 12 months have been sought, which leaves a very short period of time for the cows to be inseminated and to become pregnant. If the conception is delayed, the reproduction inefficiency can reduce milk production, causing economic problems. The calving-conception interval (CCI) depends on multiple factors such as voluntary waiting period, insemination technique, birth season, herd size and parity. Negative effects of stress caused by heat on the fertility of lactating dairy cows have been observed. An increase in body temperature decreased the probability of conception at 28 days as the number of postpartum days increased. It is known that cows with larger calving-conception intervals have more health problems. Also, they have a greater chance of being discarded, since long CCI result in longer periods with no milk production and, therefore, expenditures with unproductive cows. Moreover, an increase in the CCI from 90 to 300 days doubled the chance of discard or peripartum death in dairy matrix. This study aimed to analyze the effect of two variables: the calving - first IA interval and on the CCI of crossbred dairy cows: duration of previous calvi
Resumo
Protocolos hormonais de indução artificial de lactação constituem uma alternativa para reduzir perdas econômicas decorrentes de baixos índices reprodutivos. Objetivou-se neste estudo avaliar o efeito da indução artificial de lactação na saúde das vacas, por meio dos exames físico e complementares (hemograma e bioquímica sérica). As vacas foram submetidas ao protocolo de 21 dias de tratamento com aplicações de benzoato de estradiol, progesterona, cloprostenol, dexametasona e somatotropina bovina recombinante. Foi realizado exame físico e coleta de amostras sanguíneas semanalmente. Os animais responderam ao protocolo e apresentaram-se clinicamente saudáveis. No dia vinte e um, todos os animais apresentaram leucograma de estresse, devido à dexametasona. Os valores da enzima sérica aspartato amino transferase estiveram elevados nos momentos dia sete e dia quatorze devido à aplicação excessiva de medicação intramuscular, fosfatase alcalina e gama glutamiltransferase apresentaram valores crescentes, não caracterizando hepatopatia. Os animais mantiveram escore de condição corporal, níveis normais de colesterol, superiores de triglicerídeos, e tendência de redução do beta hidroxibutirato (BHBA). O protocolo foi eficiente ao ser implantado em vacas leiteiras mestiças e os medicamentos utilizados não interferiram na saúde dos animais.
Hormonal protocols lactation artificial induction are an alternative to reduce economic losses due to low reproductive rates. There are no studies with clinical evaluation of the animals submitted to the protocols. The objective of this study was to evaluate the effect of lactation artificial induction on the health of the animals, through the physical and complementary exams (hemogram and serum biochemistry). 12 cows were submitted to a 21-day treatment protocol with estradiol benzoate, progesterone, cloprostenol, dexamethasone and recombinant bovine somatotropin. Physical examination and blood sampling were performed weekly. The animals responded to the protocol and were clinically healthy. In D21, all animals showed stress leukogram due to dexamethasone. The AST serum enzyme values were elevated at moments D7 and D14 due to the excessive application of intramuscular medication, AF and GGT presented increasing values, not characterizing liver disease. The animals maintained body condition score, normal cholesterol levels, higher triglycerides, and a tendency to reduce beta hydroxybutyrate (BHBA). The protocol was efficient when it was implanted in crossbred dairy cows and the drugs used did not interfere in the animals health, allowing the pregnancy and the gestation of them.
Resumo
Objetivou-se avaliar dois intervalos de pastejo (IP) em lotação rotacionada ao longo de três períodos de pastejo consecutivos sobre a produtividade e a qualidade da forragem de Urochloa brizantha cv. Marandu, e seu impacto, no consumo de alimentos e água, na produção de leite individual e por hectare e na emissão de metano (CH4) entérico. Os IP foram: (i) intervalo de pastejo fixo aos 30 dias (30-IP) e (ii) quando o dossel interceptou 95% de radiação fotossinteticamente ativa (95-IL). Foram utilizadas vacas mestiças Holandês x Zebu (548 ± 61,0 kg PV), multíparas e com 70 ± 18,1 dias em lactação. O ajuste da capacidade de lotação por piquete foi feito de acordo com a técnica put-and-take, visando um resíduo pós-pastejo de 20 cm de altura. O intervalo de pastejo para o tratamento de 30-IP foi aproximadamente seis dias mais longo (P=0,01) comparado ao de 95-IL, a interceptação da luz pelo dossel forrageiro 2% maior. A massa total de forragem, colmo e massa morta por área foi maior (P<0,01) para o 30-IP em comparação com o 95- IL. No entanto, a taxa de lotação foi 11,3% maior (P=0,02) para o tratamento de 95- IL do que o de 30-IP. No período de pré-pastejo, o manejo de 95-IL apresentou maior (P<0,01) proporção de folhas e relação folha/colmo. A produtividade diária de leite e seus componentes foram de 16 a 28% maior (P<0,01) para 95-LI comparado a 30-IP, respectivamente. O conteúdo de matéria seca digestível in vitro e a concentração de PB no extrato pastejável foi maior (P0,02) para 95-IL em relação à 30-IP. A FDA e FDN no extrato pastejável foram maiores para 30-IP (P<0,01) em relação à 95-IL. O potencial de produção de gases a partir de carboidratos não fibrosos foi 9,4% superior para 30-IP. A produção de metano (CH4) expressa em g/kg de MSD foi maior (P<0,01) para 30-IP em comparação a 95-IL. A oferta de forragem foi maior (P<0,01) para 30-IP em comparação a 95-IL. O consumo de PB, a produção de leite, de lactose e sólidos totais foi maior (P<0,05) para 95-IL em comparação a 30-IP. Todavia os teores de gordura, de proteína, e sólidos totais foram maiores para 30-IP em comparação 95-IL. As emissões entéricas de CH4 in vivo e o consumo de água não foram influenciados pelo manejo (P>0,5). A média de consumo foi de 58 kg de água/d. Estes resultados sugerem que o manejo de 95-IL para o capim de Marandu, possibilitou a redução do intervalo de pastejo, melhora do valor nutritivo da forragem e aumento da produção e produtividade do leite em comparação à 30-IP. Entretanto a redução da produção de metano pelo melhor manejo da pastagem necessita ser mais investigado.
This study aimed to evaluate two grazing intervals (GI) in an intermittent stocking along three consecutive grazing periods on productivity and forage quality of Urochloa brizantha cv. Marandu, and its impact on food and water consumption, individual milk production per hectare and emission enteric methane (CH4). Grazing intervals were: (i) 30-day fixed grazing interval (30-GI) and (ii) when the canopy intercepted 95% photosynthetically active radiation (95-LI). Multiparous Holstein x Zebu cows (548 ± 61,0 kg BW) and 70 ± 18,1 days in milk (DIM) were used. The adjustment of carrying capacity per paddok was according to put-andtake technique, aiming to a post-grazing residue of 20 cm high. The grazing interval for fixed 30-GI treatment was approximately six days longer (P=0,01) than 95-IL and 2% longer light interception. The total forage mass, stem and dead mass per area were higher (P<0,01) for 30GI compared to 95-LI. However, the stocking rate was 11,3% higher (P=0,02) for 95-LI treatment than 30-GI. In the pre-grazing period, the management of 95-LI had greater leaf proportion (P<0,01) and leaf / stem ratio. Daily milk production and its components were 16 and 28% higher (P<0,01) for 95-LI compared to 30-GI, respectively. In vitro digestible dry matter (DM) content and crude protein (CP) concentration in grazing extract was higher (P0,02) for 95-LI than for 30-GI. Acid detergent fiber (ADF) and neutral detergent fiber (NDF) in the grazing extract were higher for 30-GI (P<0,01) over 95-LI. The potential for gas production from non-fibrous carbohydrates was 9,4% higher for 30-GI. The degradable dry matter in 24h was higher (P=0,03) for 95-LI compared to 30-GI. The production of methane (CH4) expressed in g/kg of degradable DM was higher (P<0,01) for 30-IG compared to 95-LI. Forage supply was higher (P<0,01) for 30-GI compared to 95-LI. CP, milk, lactose and total solids production was higher (P<0,05) for 95-IL compared to 30-GI. However, the fat, protein and total solids content was higher for 30-GI compared to 95-LI. Enteric emissions of CH4 in vivo and water consumption were not influenced by management (P> 0,5), mean consumption was 58 kg of water/day. These results suggest that the management of 95-LI for the Marandu grass enabled reduction of the grazing interval, improve nutritive value of the forage and increased milk production and productivity in relation to the 30-GI. However, the reduction of methane production due to improved pasture management needs to be investigated.
Resumo
Background: The need for high production has increased considerably in the dairy industry. On the other hand, a fertility decline has been observed in cows with best potential for milk production. Therefore, calving intervals of around 12 months have been sought, which leaves a very short period of time for the cows to be inseminated and to become pregnant. If the conception is delayed, the reproduction inefficiency can reduce milk production, causing economic problems. The calving-conception interval (CCI) depends on multiple factors such as voluntary waiting period, insemination technique, birth season, herd size and parity. Negative effects of stress caused by heat on the fertility of lactating dairy cows have been observed. An increase in body temperature decreased the probability of conception at 28 days as the number of postpartum days increased. It is known that cows with larger calving-conception intervals have more health problems. Also, they have a greater chance of being discarded, since long CCI result in longer periods with no milk production and, therefore, expenditures with unproductive cows. Moreover, an increase in the CCI from 90 to 300 days doubled the chance of discard or peripartum death in dairy matrix. This study aimed to analyze the effect of two variables: the calving - first IA interval and on the CCI of crossbred dairy cows: duration of previous calvi
Background: The need for high production has increased considerably in the dairy industry. On the other hand, a fertility decline has been observed in cows with best potential for milk production. Therefore, calving intervals of around 12 months have been sought, which leaves a very short period of time for the cows to be inseminated and to become pregnant. If the conception is delayed, the reproduction inefficiency can reduce milk production, causing economic problems. The calving-conception interval (CCI) depends on multiple factors such as voluntary waiting period, insemination technique, birth season, herd size and parity. Negative effects of stress caused by heat on the fertility of lactating dairy cows have been observed. An increase in body temperature decreased the probability of conception at 28 days as the number of postpartum days increased. It is known that cows with larger calving-conception intervals have more health problems. Also, they have a greater chance of being discarded, since long CCI result in longer periods with no milk production and, therefore, expenditures with unproductive cows. Moreover, an increase in the CCI from 90 to 300 days doubled the chance of discard or peripartum death in dairy matrix. This study aimed to analyze the effect of two variables: the calving - first IA interval and on the CCI of crossbred dairy cows: duration of previous calvi
Resumo
Reações fisiológicas como temperatura retal (TR), freqüência respiratória (FR) e temperatura da superfície corporal (TS) foram avaliadas em vacas mestiças Holandês-Zebu dos grupos genéticos 1/2 HZ, 3/4 HZ e 7/8 HZ durante dois verões e dois invernos nos períodos da manhã e da tarde no Município de Coronel Pacheco ? MG, Brasil. Adicionalmente, foram realizadas avaliações das características de pelagem e, no período da tarde, medidas de taxa de sudação. Os propósitos principais da pesquisa foram quantificar as alterações em algumas reações fisiológicas e nas características de pelagem, à luz das variações climáticas, expressas principalmente pelo índice de temperatura e umidade (ITU) e temperatura do globo negro (TGN), bem como estabelecer níveis críticos superiores desses dois índices climáticos para os grupos genéticos pesquisados. As medidas para análise de correlação e de regressão múltipla entre variáveis, foram obtidas de um grupo de 15 vacas em lactação, sendo cinco de cada um dos grupos genéticos ½ HZ, ¾ HZ e 7/8 HZ. Os efeitos de grupos genéticos, estação do ano e período do dia foram avaliados em um experimento inteiramente casualizado, estruturado em parcelas subdivididas com período do dia na subparcela e um arranjo fatorial 2 x 3 (estação do ano x grupo genético). Para avaliação da taxa de sudação e características da pelagem, adotou-se um arranjo fatorial como o citado anteriormente. Os resultados obtidos na análise de correlação, permitiram concluir que a freqüência respiratória (FR) evidenciou ser melhor indicador de estresse térmico que a temperatura retal (TR). Não foram observadas diferenças na TR e FR dos três grupos genéticos na estação de inverno e no período da manhã. A FR aumentou do inverno para o verão nos três grupos genéticos, enquanto que aumentos na TR foram constatados apenas nos animais ¾ HZ e 7/8 HZ. Do período da manhã para o da tarde foram observadas elevações nessas duas respostas fisiológicas para os três grupos genéticos. No verão e no período da tarde os animais ½ HZ apresentaram menor valor de TR que os outros dois grupos genéticos, mas sua FR foi maior apenas que a FR dos animais 7/8 HZ. A temperatura de superfície corporal (TS) aumentou nos três grupos genéticos do inverno para o verão e do período da manhã para o da tarde. Independente da estação e do período do dia a TS dos ½ HZ foi maior que a dos ¾ HZ, mas não diferiu da TS dos 7/8 HZ. Os animais 1/2 HZ apresentaram maior taxa de sudação (SUD) que os animais 3/4 HZ e 7/8 HZ, tanto no inverno como no verão, com estes últimos não diferindo entre si. Baseando-se na TR foram estabelecidos valores críticos de ITU iguais a 80; 77 e 75 e de TGN iguais a 46,0°C; 41,0°C e 38,0°C para os três grupos genéticos pesquisados. Baseando-se na FR foram encontrados valores críticos de ITU iguais a 79; 77 e 76 e de TGN iguais a 43,0°C; 40,0°C e 39,0°C para os referidos grupos genéticos, respectivamente. Com base na TS o valor crítico superior de ITU foi igual a 79 e do TGN igual a 41,0 °C para os três grupos genéticos. Os animais ½ HZ apresentaram melhores características da pelagem no verão que os 7/8 HZ, com os ¾ HZ situando-se em posição intermediária. Baseando-se nas reações fisiológicas e características da pelagem concluiu-se que as vacas ½ HZ demonstraram ser mais tolerantes ao calor ambiental do verão, e do período da tarde, independentemente da estação, que as ¾ HZ e 7/8 HZ