Cássio Cassal Brauner

Associations between resumption of postpartum ovarian activity, uterine health and concentrations of metabolites and acute phase proteins during the transition period in Holstein cows

The resumption of ovarian activity, uterine health, severity of the negative energy balance and the synthesis of inflammatory mediators during the transition period in dairy cows are interrelated. Therefore, the aim of this study was to evaluate the association between the resumption of postpartum ovarian activity and the percentage of polymorphonuclear (PMN) cells in endometrial cytology, lipid mobilization and the secretion of acute phase proteins. For this study, 20 multiparous Holstein cows were used. Blood samples that were collected from 21d before calving to 44d in milk (DIM) were analyzed for serum glucose, non-esterified fatty acids (NEFA), insulin, haptoglobin, albumin, paraoxonase and progesterone. Endometrial cytology was performed at 37±2DIM to evaluate the percentage of PMN cells in the uterine flushing. Cows were divided into two groups: (1) ovulatory cows (n=12), which returned to ovarian activity by 44±2DIM; and (2) anovulatory cows (n=8), which did not resume ovarian activity during this period. Ovulatory cows had a lower (P=0.05) percentage of PMN cells in endometrial cytology than anovulatory cows (26.3±8.3% vs. 53.4±16.9%, respectively). Ovulatory cows had higher serum albumin during the pre- (P=0.03) and postpartum periods (P=0.01), and tended to have lower haptoglobin concentrations in the prepartum period (P=0.07) and higher paraoxonase activity in the postpartum period (P=0.09). In conclusion, cows that resumed ovarian activity early in the postpartum period had higher albumin concentrations in the peripartum period, which were associated with a lower percentage of uterine PMN cells.

Different doses of equine chorionic gonadotropin on ovarian follicular growth and pregnancy rate of suckled Bos taurus beef cows subjected to timed artificial insemination protocol

This study evaluated the effect of different doses of eCG (control, 300 or 400 IU) administered at progesterone (P4) device removal in suckled Bos taurus beef cows undergoing a timed artificial insemination (TAI) protocol. A total of 966 cows received a P4 insert and 2.0 mg intramuscular estradiol benzoate at the onset of the synchronization. After 9 days, P4 insert was removed, and 12.5 mg of dinoprost tromethamine and 1 mg of estradiol cypionate were administered, followed by TAI 48 hours later. Then, the cows received one of three treatments as follows: control (n = 323), 300 (n = 326), or 400 IU of eCG (n = 317). A subset (n = 435) of cows in anestrus had their ovaries evaluated using ultrasound at the time of P4 removal and at TAI. Data were analyzed by orthogonal contrasts (C): C1 (eCG effect) and C2 (eCG dose effect). Estrous occurrence (control = 53.7%, 300 IU = 70.6%, and 400 IU = 77.0%) and pregnancy per artificial insemination (control = 29.7%, 300 IU = 44.8%, and 400 IU = 47.6%) were improved by eCG treatment (C1; P = 0.0004 and P < 0.0001, respectively). Furthermore, the cows receiving eCG presented larger follicles at TAI (control = 13.5 ± 0.3 mm, 300 IU = 14.0 ± 0.2 mm, and 400 IU = 15.1 ± 0.3 mm; P < 0.0001; C1). However, there was no effect of eCG dose on any response variables studied (C2; P > 0.15). In conclusion, the eCG treatment administered at the time of P4 removal increased the occurrence of estrus, the larger follicles at TAI, and pregnancy per artificial insemination of suckled B taurus beef cows. Despite the greater occurrence of estrus in noncyclic cows receiving 400 IU of eCG, both eCG doses (300 and 400 IU) were equally efficient to improve pregnancy to artificial insemination.

Características da lactação de vacas Hereford criadas em um sistema de produção extensivo na região da campanha do Rio Grande do Sul

Milk yield of primiparous and multiparous Hereford cows grazing native pastures was studied using 144 lactations from four different years (1995, 1998, 2000, 2001). Estimates of milk yield were obtained every 21-day interval from birth to weaning (189 d) by the weigh-suckle-weigh technique. Effects of year, calving order, pregnancy, calf sex, and sire breed were studied. Multiparous cows (8.27+0.26 kg/d) yielded more milk than primiparous cows (5.81+0.25 kg/d) at peak of lactation (42 d). Total milk yield also was higher for multiparous (1,158.34+25.51 kg/d) compared to primiparous (915.44+24.47 kg/d). Therefore, the main difference between multiparous and primiparous lactation curves was production at peak although similar lactation persistence was found. All remaining effects did not affect milk yield in the present trial. Milk met calf requirements for maintenance and growth in the first 2 months of lactation and only maintenance requirements until the fourth month.

Produção de leite e desempenho pós parto de vacas Hereford em distintas condições reprodutivas criadas extensivamente

Milk production and pospartum performance from 52 multiparous Hereford cows, with the same body condition score (3 in a 1 to 5 scale), pregnant (45) or not pregnant (24), was studied in 69 lactations during two years, 2000 (42) and 2001 (27) under range conditions. Estimates of milk yield were obtained during six intervals (three 21d and three 42d), by the weigh-suckle-weigh technique, from birth to weaning (189d). Effects studied were year, pregnancy, calf sex and sire breed. None of the effects studied affected (P>0.05) milk production parameters: daily milk production, total milk yield, lactation peak and persistency. Body weight at calving was greater (P<0.05) in 2001 (417.49 ± 6.94kg) that in 2000 (353. 97 ± 5.57kg) and was not affected by the other effects. Body weight at conception (99d; 432.10 ± 5.78 and 399,37 ± 7.92kg) and at weaning (189d; 433.30 ± 6.36 and 393.46 ± 8.70kg), were greater (P<0.05) in pregnant cows than in non-pregnant animals, respectively. Sex of calf had a significant effect (P<0.05) on calf birth weight (41.75 ± 1.21kg and 37.6 ± 1.13kg for males and females, respectively). All studied effects affected significantly calf weaning weight (P<0.05) and pregnant cows had heavier calves at weaning (194.22 ± 3.41kg) than non-pregnant cows (177.43 ± 4.67kg). The greatest performance of pregnant beef cows with similar milk yield and body condition score from calving to weaning can be explained by the superior adaptation characteristics of these cows.

Postpartum reproductive performance of beef cows in moderate body condition submitted to estrus induction/synchronization

To assess the reproductive performance of beef cows submitted to estrus induction/synchronization, 42 Aberdeen Angus cows with body condition 3 (1-5 scale) under extensive management were used. The milk production was estimated through the weight-suckling-weight method. For gynecological examinations, ultrasound equipment and trans-rectal palpation were used. The milk production level (above and below the average production of cows), pregnancy, prebreeding reproductive condition (CRPA), surface anoestrus (uterine tone, follicles > 10 mm and absence of CL) and deep anoestrus (no uterine tone, follicles <10 mm and absence of CL) and the estrus induction/synchronization response (RISC) were considered as constant factors. The variables analyzed were the pre-delivery, delivery weight, mating and conception weights, weaning weight, the average daily weight gain from birth to weaning and total milk production. The prebreeding reproductive condition influenced the pre-birth and birth weights, showing that the better pre-birth and birth performance favors the restoration of reproductive activity in cows with moderate body condition (CC) in the post-partum period. The classification of the pre-breeding reproductive condition in beef cows can be a resource to determine the reproductive performance of beef cows submitted to estrus induction/synchronization, since cows in surface anoestrus tend to have better response to the protocol. In beef cows with moderate body condition, the pre-birth weight performance affects the prebreeding reproductive condition, increasing the likelihood of better reproductive performance.To assess the reproductive performance of beef cows submitted to estrus induction/synchronization, 42 Aberdeen Angus cows with body condition 3 (1-5 scale) under extensive management were used. The milk production was estimated through the weight-suckling-weight method. For gynecological examinations, ultrasound equipment and trans-rectal palpation were used. The milk production level (above and below the average production of cows), pregnancy, prebreeding reproductive condition (CRPA), surface anoestrus (uterine tone, follicles > 10 mm and absence of CL) and deep anoestrus (no uterine tone, follicles <10 mm and absence of CL) and the estrus induction/synchronization response (RISC) were considered as constant factors. The variables analyzed were the pre-delivery, delivery weight, mating and conception weights, weaning weight, the average daily weight gain from birth to weaning and total milk production. The prebreeding reproductive condition influenced the pre-birth and birth weights, showing that the better pre-birth and birth performance favors the restoration of reproductive activity in cows with moderate body condition (CC) in the post-partum period. The classification of the pre-breeding reproductive condition in beef cows can be a resource to determine the reproductive performance of beef cows submitted to estrus induction/synchronization, since cows in surface anoestrus tend to have better response to the protocol. In beef cows with moderate body condition, the pre-birth weight performance affects the prebreeding reproductive condition, increasing the likelihood of better reproductive performance.

Reduction of liver function delays resumption of postpartum ovarian activity and alters the synthesis of acute phase proteins in dairy cows.

The aim of this study was to evaluate the concentration of acute phase proteins, milk production, and resumption of postpartum ovarian activity of clinically healthy dairy cows in a semi-extensive system with different Liver Functionality Index (LFI) values. The animals were divided into two groups: Low LFI (LLFI: -7 to -12; n: 10) and High LFI (HLFI: -7 to -4; n: 10). Animals with LLFI had lower paraoxonase activity and lower albumin concentration in the pre- and postpartum periods (P<0.05), higher non-esterified fatty acids prepartum (P<0.005), and higher haptoglobin concentration postpartum (P<0.01). The LLFI group showed lower resumption of ovarian activity until 44days postpartum (29%; P<0.05) than HLFI (86%). Milk production did not differ between groups. Therefore, this study suggests that the LFI is an important biomarker of synthesis of acute phase proteins and the first ovulation interval, and it can be used to improve the production and reproductive performance.

Effect of short period feed supplementation during early lactation on performance of cows and calves raised in extensive system

Thirty-two multiparous Angus cows at moderate body condition score (3 in a 1-5 scale) received feed supplementation at the beginning of lactation for a short time to determine the effect on milk yield and composition and on performance of cows and calves. Supplementation started on days 22 ± 3.2 after calving. The cows were randomly distributed into two groups (n =16), one group receiving feed supplementation for 35 days (supplemented group), and the other without supplementation (control group). Each cow received 0.6% of its body weight in individual troughs daily. Both groups were kept in native pasture condition during supplementation period. Milk yield evaluation, performance of cows and calves were controlled on day 0 (initial), day 14 (middle) and day 35 (final) of the supplementation period. There was no effect of feed supplementation on milk yield or on any other milk component in both groups, and on calf performance as well. Milk composition differed among periods, when fat was the highest in the middle of supplementation and lactose was the highest in the end of the period. Supplemented cows presented more daily average weight gain at the final period of supplementation than cows from the control group. Beef cow with moderate body condition score can gain weight during the lactation period as a response to increase of energy availability in a short period without any influence on milk production and composition as well as a consequence on calf performance.

Desempenho reprodutivo de vacas de corte em lactação e solteiras submetidas à indução/sincronização de estro

Com o objetivo de caracterizar o desempenho produtivo e reprodutivo de duas categorias de vacas de corte submetidas a inducao/sincronizacao de estro, foram utilizadas 42 vacas em lactacao e 60 vacas solteiras da raca Aberdeen Angus, de tamanho similar e condicao corporal moderada (CC3, escala de 1 a 5), manejadas exclusivamente em campo nativo, no periodo de setembro de 2005 a abril de 2006 no municipio de Acegua/RS. Para os exames ginecologicos durante o experimento, foi utilizado aparelho de ultra-som e palpacao retal. Como fator fixo, foi considerada a categoria das vacas (CATV), considerando-se tres grupos, vacas solteiras ciclicas (VSC), ou seja, femeas que falham em conceber e permanecem na propriedade ate o proximo acasalamento, vacas em lactacao em anestro superficial (VLAS) e vacas em lactacao em anestro profundo (VLAP). Como variaveis resposta, foram considerados peso das vacas pre-acasalamento (PPRA), pos-acasalamento (PPOA), a concepcao (PC), o ganho de peso medio diario durante o acasalamento (GMD), resposta ao protocolo de inducao/sincronizacao de cio (RISC) e gestacao. A categoria da vaca demonstrou efeito (P<0,0001) sobre as variaveis de peso, em que as VSC apresentaram um melhor desempenho ponderal do que VLAS e VLAP. A RISC demonstrou ser altamente influenciada (P<0,0001) pela categoria de vaca, em que 85, 45 e 35% das vacas responderam a inducao/sincronizacao de cio nos grupos VSC, VLAS e VLAP, respectivamente. A gestacao apresentou diferenca (P<0,0001) entre VSC e vacas em lactacao, com 96,7, 45,5 e 30,0%, nos respectivos grupos VSC, VLAS e VLAP. Vacas solteiras apresentam um desempenho reprodutivo superior ao de vacas em lactacao, evidenciado pela maior resposta ao protocolo de inducao/sincronizacao de estro e indice de gestacao. Contudo, 24% das vacas em lactacao parecem estar bem adaptadas ao sistema de producao, demonstrando um desempenho produtivo e reprodutivo satisfatorio a producao de bovinos de corte, sendo capazes de produzir adequadamente leite para o desenvolvimento dos terneiros, bem como conceber e produzir novamente um terneiro. A identificacao desses animais pode influenciar positivamente o desempenho reprodutivo de vacas de corte em lactacao.

Desempenho reprodutivo de novilhas de corte expostas a diferentes métodos de bioestimulação

EnglishThe objective of this study was to evaluate the reproductive performance of beef heifers exposed or not to different sexual biostimulation treatments. Two hundred and twenty Aberdeen Angus heifers, 24 months old were used. Heifers were divided into three groups: group one, using teaser bull consisted of 73 heifers exposed, for 60 days previous to AI, to vasectomized males. The second group consisted of 73 heifers exposed during the same period to androgenized cows. The third group consisting of 74 heifers was the control group. After the treatments (60 days) started the breeding season. Variables analyzed were the weight at the beginning and the end of treatment, ADG, the pregnancy rate, and the interval between the start of breeding season and conception. Fixed factors considered were the three treatments. Heifers biostimulatated with androge- nized cows had a earlier conception, (p Biostimulation can not change rates of pregnancy in beef heifers. The use of biostimulation with cows androgenized anticipates the conception in beef heifers of two years old. portuguesO objetivo deste estudo foi avaliar o desempenho reprodutivo de novilhas de corte submetidas a diferentes metodos de bioestimu- lacao. Foram utilizadas 220 novilhas Aberdeen Angus de dois anos de idade. Setenta e tres novilhas foram mantidas com machos caudecto- mizados, 73 com vacas androgenizadas e 74 nao receberam tratamento bioestimulatorio. Os tratamentos tiveram duracao de 60 dias pre- acasalamento. Os fatores fixos analisados foram os tres tratamentos. As variaveis resposta foram os pesos ao inicio e fim dos tratamentos, ganho medio diario (GMD), o indice de prenhez e dias para a concepcao (medido atraves da data de parto ajustada a data de inseminacao). Nao houve diferenca (p>0,05) nos indices de prenhez obtidos entre os tratamentos. A concepcao foi antecipada (p

AVALIAÇÃO DO EFEITO DO TOURO E DA CONDIÇÃO CORPORAL NA TAXA DE PRENHEZ DE VACAS SUBMETIDAS AO PROTOCOLO DE INSEMINAÇÃO ARTIFICIAL EM TEMPO FIXO

O objetivo deste trabalho foi avaliar a influencia da condicao corporal de 3 e 3,5 e do impacto do desempenho de touros na taxa de prenhez de vacas da raca Braford lactantes criadas em campo nativo submetidas a inseminacao artificial em tempo fixo (IATF). Para isso, foram selecionas de um rebanho comercial 216 vacas da raca Braford, multiparas e lactantes com escore de condicao corporal (ECC) de 3,0 e 3,5, as quais foram submetidas ao mesmo protocolo de IATF. As vacas foram aleatoriamente designadas a inseminacao com um dos dois touros (A e B) em avaliacao no presente estudo. O diagnostico de gestacao de 30 dias apos a inseminacao artificial foi realizado atraves de exame ultrassonografico. Nao foi observado qualquer efeito, tanto do touro quanto do ECC, sob a taxa de prenhez das vacas, porem, foi possivel observar que a porcentagem de animais vazios foi relativamente alta (ECC 3,0 = 71,6%; ECC 3,5= 72%). Nao foi observado efeito do ECC e do touro sobre a taxa de prenhez de vacas Braford submetidas a IATF.