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IEPL; International audience; It has been previously shown that the long-term inhibition of milking-induced prolactin (PRL) release by quinagolide (QN), a dopamine agonist, reduces milk yield in dairy cows. To further demonstrate that PRL is galactopoietic in cows, we performed a short-term experiment that used PRL injections to restore the release of PRL at milking in QN-treated cows. Nine Holstein cows were assigned to treatments during three 5-d periods in a 3 × 3 Latin square design: 1) QN: twice-daily i.m. injections of 1 mg of QN; 2) QN-PRL: twice-daily i.m. injections of 1 mg of QN and twice-daily (at milking time) i.v. injections of PRL (2 µg/kg body weight); and 3) control: twice-daily injections of the vehicles. Mammary epithelial cells (MEC) were purified from milk so that their viability could be assessed, and mammary biopsies were harvested for immunohistological analyses of cell proliferation using PCNA and STAT5 staining. In both milk-purified MEC and mammary tissue, the mRNA levels of milk proteins and BAX were determined using real-time reverse-transcription PCR. Daily QN injections reduced milking-induced PRL release. The area under the PRL curve was similar in the control and PRL injection treatments, but the shape was different. The QN treatment decreased milk, lactose, protein, and casein production. Injections of PRL did not restore milk yield but tended to increase milk protein yield. In mammary tissue, the percentage of STAT5-positive cells was reduced during QN but not during QN-PRL in comparison with the control treatment. The percentage of PCNA-positive cells was greater during QN-PRL injections than during the control or QN treatment and tended to be lower during QN than during the control treatment. In milk-purified MEC, κ-casein and α-lactalbumin mRNA levels were lower during QN than during the control treatment, but during QN-PRL, they were not different from the control treatment. In mammary tissue, the BAX mRNA level was lower during QN-PRL than during QN. The number of MEC exfoliated into milk was increased by QN injections but tended to be decreased by PRL injections. Injections of PRL also increased the viability of MEC harvested from milk. Although PRL injections at milking could not reverse the effect of QN treatment on milk production, their effects on cell survival and exfoliation and on gene expression suggest that the effect of QN treatment on the mammary gland is due to QN's inhibition of PRL secretion.

High-quality colostrum is an important factor influencing neonatal calf health, and quality assessment is essential to obtain good health results. This research evaluated the effects of the calf’s sex, the parity of the cow and the hour of colostrum harvest after parity on the fat, nonfat solids, protein and Ig contents in Holstein colostrum for cows under high grazing conditions in the tropics. The effects of the calf’s sex and parity on somatic cell count (SCC) at the first milking postpartum were determined. A comparison was made between a laboratory method and a farm method for the estimation of the fat and protein content of colostrum. Thirty-three cows were sampled in the study. The calf’s sex was shown to have an effect on the amount of colostrum, on the concentration of fat, and on the amount of milk produced by lactating Holstein cows; all were higher in cows that gave birth to a female calf. Colostrum protein decreased after the first hour postpartum, and the Ig concentration had a tendency to decrease after 4 h. The cows that had parity 1–2 had lower Ig concentrations and total production of Igs, and higher SCC at the first milking postpartum. Ekomilk was a reliable method to measure the colostrum fat on the farm. COL0009556

Este trabalho foi desenvolvido na Universidade Tecnológica Federal do Paraná, Câmpus Dois Vizinhos, com o objetivo de comparar diferentes modelos matemáticos de base empírica ou mecanicista, quanto à qualidade de ajuste e poder de predição das curvas de lactação, obtidas por meio de dados provenientes do controle leiteiro da APCBRH de rebanhos da região sudoeste do Paraná. Foram obtidos inicialmente 42.281 controles de produções leiteiras referentes aos anos de 2005 a 2011,dos quais foram excluídas as informações de animais que não possuíam a data de secagem e a produção total aos 305 dias, restando 15.142 controles referentes à 2441 vacas da raça holandesa. Os dados utilizados foram classificados de acordo com a ordem de parição das vacas (variando de um a seis), e dentro de cada ordem de parição os animais foram separados em quartis (Q25%, Q50%,Q75% e Q100%) conforme a produção total aos 305 dias. Para cada quartil, dentro de cada ordem de parição foram ajustados quatro modelos matemáticos, dois predominantemente empíricos (modelo de Brody e de Wood) e dois com características mais mecanicistas (modelo de Djikstra e de Pollot) usando o proc nlin do SAS método de Marquardt. O de Wood resultou na melhor qualidade de ajuste aos dados. Entretanto os modelos de Brody e Dijkstra também devem ser considerados para descrever as curvas de lactação de vacas holandesas criadas na região sudoeste do Paraná, por apresentarem desempenho muito semelhante, em que o modelo Dijkistra possui uma descrição biológica dos parâmetros e permite uma conotação fisiológica da curva de lactação. Ressaltando o valor histórico do modelo de Brody como pioneiro em modelagem de curva de lactação. His work was developed at Federal Technological University of Paraná, Câmpus Dois Vizinhos, aiming to analyze different mathematical models comparing empirical and mechanistic models, as their fit and predictive power of the lactation curves obtained using data from the control of dairy APCBRH herds in the southwest region of Paraná, where the evaluation and analysis of 42.281 controls milk production for the years 2005 to 2011, where information from animals that didn´t have the date of drying and total output to 305 days were excluded from the set of data analysis, leaving 15.142 controls concerning the 2.441 Holstein cows, classifying the data according to the order of calving cows (ranging from one to six) and within each order of calving animals were divided into quartiles (Q25% Q50%, Q75% and Q100%) as the total output to 305 days. For each quartile within each lactation numbers were adjusted four mathematical models, two predominantly empirical model (Brody and Wood) and two with more mechanistic characteristics (model Djikstra and Pollot) using SAS proc nlin Marquardt method. Obtaining the Wood model as a result of best fit to the data. However the use of models and Brody Dijkstra to describe lactation curves of Holstein cows raised in the southwestern region of Paraná, should be considered as an option because they have very similar performance, where the model Dijkistra has a biological description of the parameters and allows a connotation physiological lactation curve. Emphasizing the historical value of the model Brody as a pioneer in modeling lactation curve.

Bu çalışma, Bursa ili Nilüfer ilçesi Akçalar beldesinde bulunan GTZ ( Alman Teknik işbirliği Kuruluşu ) ve Bursa Holştayn (Siyah Alaca) Damızlık İşletmeler Birliği tarafından birlikte uygulanan Sığır Yetiştiriciliği Soykütüğü Projesine bağlı yirmi ayn işletmede bulunan Siyah Alaca sığırların döl verimi ve süt verimi özelliklerinin düzeylerini belirlemek ve bu verim özelliklerine çevre faktörlerinin etkilerini incelemek amacıyla yapılmıştır. Araştırma süresince ( 1994 - 1996 ) gebelik, doğum, ölü doğum ve yavru atma oranlan sırasıyla % 58.15, %87.83, %1.66 ve %2.85 olarak saptanmıştır. Siyah Alaca düvelerin ilk tohumlama yaşı, ilk tohumlama - gebelik aralığı, servis sayısı ve ilk buzağılama yaşı ortalamaları sırasıyla; 546.06 gün, 13.11 gün, 1.35 ve 834.09 gün olarak bulunmuştur. Siyah Alaca ineklerin doğum sonrası ilk tohumlama aralığı, ilk tohumlama - gebelik aralığı, servis peryodu, servis sayısı, buzağılama aralığı ve gebelik süresi ortalamaları sırasıyla; 86.83 gün, 46.37 gün, 135.47 gün, 1.95, 408.20 ve 278.36 gün olarak bulunmuştur. Siyah Alaca ineklerin laktasyon süresi, gerçek süt verimi, 2 x 305 gün süt verimi ve kuru dönem süresi ortalamaları sırasıyla; 341.06 gün, 5291.20 kg, 4863.60 kg ve 80.25 gün olarak ı bulunmuştur. Çevre faktörlerinden tohumlama ya da buzağılama yılı, döl verimi özelliklerinden düvelerde ilk tohumlama yaşını ve'ilk buzağılama yaşını; ineklerde doğum sonrası ilk tohumlama aralığını, gebelik süresini ve laktasyon süresini etkilemiştir. Çevre faktörlerinden işletmeler, döl verimi özelliklerinden düvelerde ilk buzağılama yaşını; ineklerde ilk tohumlama - gebelik aralığını, servis peryodunu, servis sayısını ve buzağılama aralığını etkilemiştir. Çevre faktörlerinden mevsimler, döl verimi özelliklerinden gebelik süresini etkilemiştir. Çevre faktörlerinden buzağılama yılı süt verimi özelliklerinden laktasyon süresini etkilemiştir. Çevre faktörlerinden işletmeler, süt verimi özelliklerinden gerçek süt verimini, 2 x 305 süt verimini ve kuruda kalma süresini etkilemiştir. Çevre faktörlerinden yaş grupları, süt verimi özelliklerindenlaktasyon süresini ve 2 x 305 gün süt verimini etkilemiştir. Çevre faktörlerinden mevsimler, gerçek süt verimini ve 2 x 305 gün süt verimini etkilemiştir. Çevre faktörlerinden her türlü ikili interaksiyonlann etkisi, söz konusu döl ve süt verimi özelliklerine istatistiki yönden önemli bulunmamıştır. This study was performed for determining the levels of reproduction characteristics and milk yield characteristics of Hoistein - Friesian in twenty Hoistein - Friesian Breeding Farms in Akçalar - Bursa Turkey and examining the effects of environmental factors upon them. Those Hoistein Friesian farms belong to GTZ (German Technical Coorperation) project and they are members of DIB (Bursa Hoistein Friesian Breeding Farms Coorperation). During the research (1994 - 1996) the rates of conception, birth, dead birth and abort for the Hoistein Friesian Cows were determined %58.15, %87.83, %1.66 and %2.85 respectively. At Hoistein - Friesian heifers, the age at first insemination, interval from first insemination to conception, number of inseminations per conception and the age at first calving means were found 546.06 days, 13.11 days, 1.35 and 834.09 days respectively. For the Hoistein - Friesian cows interval from calving to first insemination, interval from first insemination to conception, days open, number of insemination per conception, calving interval and gestation length means were determined 86.83 days, 46.37 days, 135.47 days, 1.95, 408.20 days and 278.36 days respectively. For the Hoistein Friesian cows lactation length, the actual milk yield, 2 x 305 days milk yield and dry period means were determined as 341.06 days, 5291.20 kg, 4863.60 kg and 80.25 days respectively. At heifers, the age of first insemination and the age of first calving; at cows interval from calving to first insemination, gestation length and lactation length were affected by mating and calving year. Also at heifers age at first carving; at cows interval from first insemination to conception, days open, number of insemşnations per coception and calving interval were affected by farms that is one of the environmental factors. Also at cows gestation length is affected by seasons. Lactation length of cows is affected by calving yar that is one of the environmental factors. At cows actual milk yield, 2 x 305 days milk yield and dry period were affected by farms that is one of the environmental factors. Lactation length of cows and 2 x 305 days milk yield were affected by age groups that is one of the environmental factors. Both at heifers and at cows the reproduction and milk yield characteristics were not affected all of both interactions of the environmental factors.