Performance Of Holstein Cows Research Articles

Defining delayed resumption of ovarian activity postpartum and its impact on subsequent reproductive performance in Holstein cows

The objectives of this study were to derive a useful case definition of delayed resumption of ovarian activity, based on factors associated with reduced fertility, and to assess its impact on subsequent reproductive performance in Holstein cows ( Bos taurus). Milk samples were collected twice weekly from 219 cows from four commercial herds, and whole-milk progesterone concentrations were determined with an enzyme-linked immunosorbent assay. Ovulation was considered to have occurred 5 d before the first rise of milk progesterone concentration above the basal level. Survival analysis was used to derive a case definition of delayed resumption of ovarian activity postpartum based on factors that were predictive of reduced pregnancy rate. First postpartum ovulation occurring beyond 35 d postpartum was associated with a reduced pregnancy rate (hazard ratio [HR] = 0.50; P < 0.001) and was defined as delayed resumption of ovarian activity; overall, 75 (34.9%) cows were in this category. These cows were more likely not to conceive on first artificial insemination (odds ratio [OR] = 2.85; P = 0.01) and more likely not to become pregnant within 100 d (OR = 3.30; P = 0.001) and 210 d (OR = 3.20; P < 0.001) postpartum compared with cows with normal resumption of ovarian activity. Furthermore, 13 (6%) cows that ovulated within 35 d postpartum had a prolonged (≥14 d) interval between either first and second or second and third luteal phases postpartum. A prolonged interluteal interval was also associated with a reduced pregnancy rate (HR = 0.35; P = 0.02). Days open (mean ± SEM) were greater (P = 0.0002) in cows with delayed resumption of ovarian activity (213 ± 13 d) and in cows with prolonged interluteal interval (220 ± 37 d) than in cows with normal resumption of ovarian activity (152 ± 9 d). In conclusion, first ovulation occurring beyond 35 d postpartum was defined as delayed resumption of ovarian activity, and the first ovulation occurring within 35 d postpartum but the absence of luteal activity ≥14 d between two consecutive luteal phases was defined as a prolonged interluteal interval; both abnormalities adversely affected the subsequent reproductive performance of Holstein cows.

Prevalence of urovagina and its effects on reproductive performance in Holstein cows

Two hundred fifty-eight Holstein cows (n = 344 lactations) from seven dairy herds were examined every month by vaginoscopy and transrectal palpation to determine the prevalence of urovagina, to investigate its effects on fertility, and to determine some risk factors for urovagina. Accumulation of urine in the vagina of a cow was diagnosed as urovagina and was classified into mild (urine only on the floor of vagina), moderate (urine covering less than or equal to half portion of the external cervical os), or severe (urine covering more than half or whole portion of the external cervical os). In total, 26.7% of lactations had urovagina (mild 11.3%, moderate 11.0%, and severe 4.4%). Survival analysis was used to derive the case definition of clinically relevant urovagina based on the factors associated with increased time to conception. Only moderate (hazard ratio [HR] = 0.39) and severe (HR = 0.20) degrees of urovagina were associated with reduction in pregnancy rate and thus defined as clinically relevant urovagina. Cows with clinically relevant urovagina had decreased AI submission rate (HR = 0.52) and pregnancy rate (HR = 0.35), required more inseminations per conception (5 vs. 2; P < 0.001), had more days open (370 vs. 136; P < 0.001), and were more likely not to get pregnant by 210 d postpartum (odds ratio [OR] = 6.62) and to be culled for any reasons (OR = 5.32) or for reproductive reasons (OR = 9.54) compared with those in cows with no urovagina. Cows with clinically relevant urovagina had a higher risk of endometritis (36.4% vs. 9.2%; P < 0.001) compared with that in cows without urovagina. Cow, low BCS at first postpartum examination (OR = 2.85), endometritis within 60 d (OR = 2.50), and horizontal vulva (OR = 9.30) were risk factors for urovagina. In conclusion, 15.4% of lactations had clinically relevant urovagina that increased the risk of endometritis and had detrimental effects on fertility. Individual susceptibility, low BCS, and horizontal vulva increased the risk of diagnosing urovagina in Holstein cows.

Ovarian Cyclicity and Reproductive Performance of Holstein Cows Carrying the Mutation of Complex Vertebral Malformation in Japan

This study was carried out on 71 lactating Holstein Friesian cows to investigate the resumption of ovarian cyclicity postpartum and the reproductive performance in cows carrying the mutation of complex vertebral malformation (CVM) compared with control ones. The cows were distributed in two dairy farms in Hiroshima Prefecture, Western Japan. Blood samples were collected from the cows to detect carrier cows with CVM mutation. Furthermore, plasma samples were collected weekly after calving from control cows (n = 10) and CVM carrier cows (n = 10), until 10 weeks postpartum to investigate the day of first ovulation and the resumption of ovarian cyclicity postpartum. The reproductive parameters were investigated and compared with control and CVM carrier cows. Thirty-six cows were diagnosed to be CVM carriers by DNA examination and confirmed later by DNA sequencing. The pedigree analysis of the carrier cows revealed that they were daughters of six types of CVM carrier semen that still was used in dairy farms in Western Japan. In terms of reproductive indices, there were no significant differences between the control and the CVM carrier cows on the day of the first ovulation postpartum and the interval from calving to first insemination. However, CVM carrier cows significantly required more inseminations per conception and showed a significantly longer period to conception and subsequent calving than control ones. In conclusion, the reproductive performance of the CVM carrier cows was lowered through conception failure that might indicate the occurrence of intra-uterine mortality in those cows.

Effects of Clinical Mastitis on Reproductive Performance in Holstein Cows

The objective of this study was to determine the effects of clinical mastitis on reproductive performance in 135 early lactation cows. The animals were divided into two groups according to the occurrence of mastitis as follows: group I (n = 45), clinical mastitis prior to the first artificial insemination breeding; group II (n = 45), clinical mastitis after artificial insemination and being diagnosed pregnant. Forty-five cows without any mastitis served as control group. Calving to first service intervals were significantly longer (P &lt; 0.05) in cows with clinical mastitis before first service (group I; 95.2 ± 5.4 d) than in cows with clinical mastitis after first service (group II; 77.4 ± 8.2 d) and in control cows (75.9 ± 6.3 d). Calving to conception interval with clinical mastitis before first service (119.1 ± 10.6 d) and in cows with clinical mastitis after first service (141.7 ± 14.0 d) was significantly longer (P &lt; 0.05) than in control (94.1 ± 10.3 d) cows. On the other hand, the number of services per conception was larger (P &lt; 0.05) in cows with clinical mastitis after first service (3.4 ± 0.9) than in cows with clinical mastitis before first service (2.1 ± 0.9) and in cows with no clinical mastitis (1.8 ± 0.8). This study indicated that clinical mastitis during early lactation in Holstein cows had a negative impact on their reproductive performance.

Efeito do concentrado no desempenho produtivo, reprodutivo e econômico de vacas da raça Holandesa em pastagem de coast-cross

Avaliou-se o desempenho produtivo, reprodutivo e econômico de vacas da raça Holandesa, mantidas em pastagem de capim-coast-cross e suplementadas com 3 ou 6kg de concentrado/vaca/dia. O pastejo foi sob lotação rotacionada, com um dia de ocupação dos piquetes e 25 ou 35 dias de descanso nas épocas de chuvas ou de seca, respectivamente. A produção de leite foi influenciada pela quantidade de suplemento fornecida. Vacas que receberam 6kg de suplemento produziram mais leite (19,1kg/dia) do que as que receberam 3kg (15,5kg/dia). O primeiro estro pós-parto ocorreu aos 99,9 e 67,8 dias, respectivamente, pelos métodos de identificação visual e dosagem de progesterona, para vacas suplementadas com 3kg de concentrado, e 72,9 e 54,5 dias para as suplementadas com 6kg; os intervalos de partos, obtidos na mesma ordem dos tratamentos citados, foram de 444,8 e 436,8 dias. O método visual para identificação de estros não foi preciso e comprometeu a rentabilidade da atividade.

Desempenho de vacas da raça Holandesa em pastagem de coastcross

Avaliou-se o desempenho produtivo de vacas da raça Holandesa mantidas em pastagem de coastcross (Cynodon dactylon (L.) Pears) fertilizada, irrigada e suplementada com 3 ou 6 kg de concentrado/vaca/dia. Dados de 108 lactações coletados durante três anos consecutivos (outubro/2000 a outubro/2003) foram analisados em um delineamento de blocos ao acaso com duas repetições por tratamento, utilizando-se nove animais por área e 18 por tratamento, com lotação fixa de cinco vacas/ha. Adotou-se o sistema de pastejo em lotação rotacionada, com um dia de ocupação e 25 e 35 dias de descanso dos piquetes, nas estações chuvosa e seca, respectivamente. A pastagem foi irrigada nos meses de menor precipitação e fertilizada com adubo formulado (NPK), distribuído a lanço em seis aplicações anuais. A disponibilidade de matéria seca foi de 7.280 e 6.167 kg/ha no início do pastejo, com resíduo pós-pastejo de 4.885 e 3.994 kg/ha, nas estações chuvosa (primavera/verão) e seca (outono/inverno), respectivamente. Durante parte do período experimental, algumas características morfogênicas da pastagem foram avaliadas, registrando-se disponibilidade de 83,9; 125,6 e 89,5 kg de MS de lâminas foliares/ha, nas estações de primavera, verão e outono, respectivamente. As produções médias diárias de leite (corrigidas para 3,5% de gordura) foram de 15,5 e 19,1 kg/vaca e de 77,8 e 94,0 kg/ha, quando foram fornecidos, para cada vaca, 3 e 6 kg de concentrado, respectivamente. Pastagem de coastcross, quando fertilizada e manejada adequadamente, viabiliza elevadas produtividades de leite por animal e por área, podendo ser recomendada para produção de leite em pastagens.

Effect of yeast culture, fungal fermentation extract and non-ionic surfactant on performance of Holstein cows during transition period

The effects of yeast ( Saccharomyces cerevisiae) culture (SC), fungal ( Aspergillus oryzae) fermentation extract (AO) and non-ionic surfactant (NIS) as feed additives on dry matter intake (DMI) and milk production of dairy cow were investigated. Forty Holstein dairy cows were equally assigned to four treatments including the control in randomized block design, and fed the total mixed rations supplemented 20 g, 100 g and 50 mL day −1 head −1 for SC, AO and NIS during prepartum period, and 30 g, 150 g and 50 mL day −1 head −1 for SC, AO and NIS during postpartum period, respectively. Cows fed the diets supplemented SC or AO had greater (P<0.05) DMI in the transitional period (−2 day, 0 day, +1 day of calving) than when fed the basal diet or NIS, but had no effect in prepartum (21 and 2 days) and postpartum (7, 21 and 42 days) periods. During entire experimental period, DMI was not significant difference between the control and NIS. Average milk production during the period of postpartum investigated was not influenced by supplementation of feed additives. Milk fat content, however, was significantly (P<0.05) increased about 3.9% in cows fed the diets supplemented AO or NIS compare to the control.

Comparison of a Corn Silage Hybrid with High Cell-Wall Content and Digestibility with a Hybrid of Lower Cell-Wall Content on Performance of Holstein Cows

We hypothesized that substituting a corn hybrid with high cell-wall content and high neutral detergent fiber (NDF) digestibility (HCW) for a hybrid with lower cell-wall content and lower NDF digestibility (LCW) would improve feed intake and milk production in lactating Holstein cows. There was a 3.6 percentage unit difference in NDF content and a 4.1 percentage unit difference in 30-h in vitro NDF digestion between the 2 corn hybrids. In trial 1, 40 cows (12 primiparous) ranging in milk production from 24.1 to 44.0 kg/d, following a 2-wk preliminary period, were used in a crossover design with 2-wk periods. Diets consisted of 45% corn silage (HCW or LCW), 10% alfalfa hay, and 45% concentrates. The DMI (25.4 vs. 24.2 kg/d) and 4% FCM yield (34.3 vs. 31.7 kg/d) were higher for cows fed the HCW diet compared with the LCW diet. When HCW was substituted for LCW on a DM basis, there was no relationship between pretrial milk yield (preliminary period) and subsequent response to HCW silage. In trial 2, 40 cows (8 primiparous) ranging in milk production from 20.6 to 49.0 kg/d, following a 2-wk preliminary period, were used in a crossover design with 2-wk periods. Diets consisted of the same LCW diet as trial 1 and a diet containing HCW at a concentration (40% of DM) that resulted in equal NDF content (30.8%) between the 2 diets (HCWN). The DMI (26.8 kg/d) was unaffected by diet, although there was a trend for greater DMI (% of BW) for cows fed the HCWN diet compared with LCW silage (4.24 vs. 4.12). Milk fat (3.91 vs. 3.79%) and 4% FCM yield (34.9 vs. 33.4 kg/d) were greater for cows fed HCWN vs. LCW diet. When HCW was substituted for LCW silage on an NDF basis, cows with greater milk production during the preliminary period had a greater milk response to HCW than lower-producing cows. Results of these trials supported our hypothesis that HCW corn silage results in greater DMI and milk yield than LCW silage, whether substitution occurs on a DM or NDF basis.

청예사료작물과 볏짚 위주의 완전배합발효사료 급여가 Holstein 착유우의 생산성에 미치는 영향

본 연구는 6종류의 완전배합발효사료(Total mixed fermentation feed; TMFF)의 착유우에 대한 영양적 가치를 구명하고자 수행되었다. 옥수수, 혼합목초, 호맥, 유채, 알팔파 및 연맥의 6종의 사료작물 청예가 수확되었고, 볏짚과 밀기울이 배합되었으며, 옥수수와 콩알곡을 배합하였다. 그리고 각각의 배합물들은 40톤 규모의 트렌치 사일로에 진압 저장하였으며, 성분분석과 젖소 급여시험을 위해 최소 60일 이상 경과 후에 개봉하였다. TMFF의 평균 건물 함량은 23.98<TEX>${\sim}$</TEX>28.42% 범위였으며, 조단백질 함량은 16.2<TEX>${\sim}$</TEX>19.2%이었고, 가소화영양소총량(TDN)은 58.3<TEX>${\sim}$</TEX>65.1% 수준이었다. ADF 함량은 34.4<TEX>${\sim}$</TEX>39.6% 범위에서, NDF 함량은 46.9<TEX>${\sim}$</TEX>49.9% 범위를 나타내어 상대적사료가치(RFV)는 유채-, 알팔파-, 혼합목초-, 연맥-, 옥수수-. 호맥-TMFF에서 각각 138.6, 133.9, 116.5, 111.8, 111.4, 108.1으로 나타나, 호맥-TMFF의 것이 유의하게 낮은 것으로 나타내었다(P<0.05). 건물손실율은 0.8<TEX>${\sim}$</TEX>1.9% 범위로서 모든 TMFF에서 양호한 발효와 보관상태를 나타내었으며, pH는 전체적으로 3.89<TEX>${\sim}$</TEX>4.87이었으며, 암모니아태질소(<TEX>$NH_3$</TEX>-N) 함량은 6.93-8.66 mg/㎗이었다. 그리고 TMFF 원물내의 휘발성지방산 함량 중 초산 함량은 0.19<TEX>${\sim}$</TEX>0.57% 낮은 함량을 나타내었고, 젖산 함량은 1.17<TEX>${\sim}$</TEX>3.21%으로 매우 높게 나타내었으며, 부틸산 함량은 0.03<TEX>${\sim}$</TEX>0.32%로서 매우 낮게 나타나 TMFF의 품질이 양호한 것으로 나타내었다. 그리고 발효가 완료된 TMFF를 평균 착유일수 240일, 2.4산차, 44.3개월령, 일일산유량 21.2 kg, 체중 574.6 kg, 체충실지수(BCS) 3.2인 42두에 무제한으로 급여하여 총 60일간의 섭취량 조사와 월별 체중 및 BCS를 조사한 결과, 초종별 TMFF의 평균 일일 총 섭취량은 알팔파-, 혼합목초-, 유채-, 옥수수-, 연맥-, 호맥-TMFF구에서 62.85, 60.48, 58.04, 57.11, 54.61, 45.74 kg의 순서로 각각 높게 나타내어 전체적으로 기호성이 우수한 것으로 나타내었으며, 호맥-TMFF구의 기호성이 가장 낮게 나타내었다(P<0.05). 이때 젖소의 체중에 대한 TMFF의 건물섭취율은 1.95<TEX>${\sim}$</TEX>2.90%로서 모든 TMFF의 기호성이 매우 우수한 것을 알 수 있었다. TMFF의 급여시험기간 중의 체중변화와 체충실지수(BCS)에 있어서 시험기간 60일 동안 모든 공시축에서 체중증가가 있었으며, 기간의 평균 두당 일당증체량은 140.0<TEX>${\sim}$</TEX>326.7g으로서 기호성이 가장 좋았던 알팔파-TMFF구에서 역시 가장 높은 증체를 보였으며, 기호성이 가장 낮았던 호맥-TMFF구에서 가장 낮은 증체를 나타내었다(P<0.05). 신체충실지수의 변화에 있어서는 혼합목초-TMFF구가 개시시의 3.07에서 3.34로 가장 크게 증가하였고, 호맥-TMFF구에서 3.34에서 3.30으로 약간 감소하여 나타냄으로서 증체량과 신체충실지수와는 비슷한 경향을 보였으나 일치하지는 않은 것으로 나타내었다(P<0.05). 그리고 평균 두당 우유생산성은 알팔파-, 연맥-, 혼합목초-, 옥수수-, 유채-, 호맥-TMFF구의 순서로 일일평균 16.16-18.95 kg 범위에서 시험구간에 유의한 차이를 나타내었으며(P<0.05), 일일 산유량의 변화에 있어서는 시험개시시의 평균 21.2kg에서 60일 후 시험 종료시에 모든 시험구에서 5kg 정도 감소하여 나타내었는데, 이는 시험종료시는 대부분의 시험축의 착유일수가 300일 이상의 비유말기에 이르렀기 때문으로 사료된다. 우유의 성분 함량에 있어서 시험기간 중 평균지방 함량은 전체적으로 4.06<TEX>${\sim}$</TEX>4.79% 범위에서 매우 높은 유지방 함량을 나타내어 유채-, 혼합목초-, 옥수수-, 알팔파-, 호맥-, 연맥- TMFF구의 순서로 높았으며, 단백질 함량은 3.15<TEX>${\sim}$</TEX>3.54% 범위에서 혼합목초-, 옥수수-, 유채-, 호맥-, 연맥-, 알팔파-TMFF구의 순서로 높게 나타내었다. 또한, 유당 함량에 있어서는 전체 평균이 4.56% 내외로서 서로 비슷한 함량을 나타내었으며, 무지고형분량과 총 고형분 함량에 있어서도 전체 평균이 8.75%와 12.8% 내외로 시험구간에 차이가 없는 것으로 나타내었는데, TMFF 급여에 의해 우유중 성분 함량에 있어서 어떠한 경향을 찾을 수 없었다. This experiment was carried out to evaluate the value of total mixed fermentation feeds(TMFF) as completely mixed ration and to observe the effect of various kinds of TMFF on the palatability, feed intake, and milk performance in Holstein cows. The dry matter (DM) content of TMFF used in the experiment was 23.98-28.42% range, and CP, TDN, ADF and NDF were 16.2<TEX>${\sim}$</TEX>19.2%, 58.3-65.1%, 34.4-39.6% and 46.9<TEX>${\sim}$</TEX>49.9% levels, respectively. The relative feed value (RFV) in rape-, alfalfa-, grass-, oat-, corn-TMFF groups were 138.6, 133.9, 116.5, 111.8, 111.4 and 108.1, respectively. Among these groups, RFV of rye-TMFF group was lowest. Dry matter disappearance(DMD) showed 0.8<TEX>${\sim}$</TEX>.9% to the all kinds of TMFF groups. The pH was 3.89<TEX>${\sim}$</TEX>.87 and <TEX>$NH_3$</TEX>-N concentration was 6.93-8.66 mg/<TEX>$d\ell$</TEX>. The acetic acid concentration in the raw material of TMFF showed low level of 0.19<TEX>${\sim}$</TEX>0.57%, lactic acid showed high level of 1.17<TEX>${\sim}$</TEX>3.21% and butyric acid was very high as 0.03<TEX>${\sim}$</TEX>0.32%. Therefore, these results provide evidence that the quality of TMFF was not so bad. In the daily fresh matter intake on the alfalfa-, grass-, rape-, corn-, oats- and rye-TMFF were showed 62.85, 60.48, 58.04, 57.11, 54.61 and 45.74 kg respectively. All TMFF showed high palatability as daily dry matter intake of 1.95 to 2.90% by body weight of experimental cows. Body condition score(BCS) was gradually increased in during 60 days of the experiment term. Average daily gain(ADG) showed about 140.0<TEX>${\sim}$</TEX>326.7g. In alfalfa-TMFF group, the ADG was higher than in the other groups (p<0.05). Also, the increase in BCS was observed in grass-TMFF group (3.07 to 3.34) and rye-TMFF group was decreased in 3.07 to 3.34 (p<0.05). The milk yield appropriately showed a range of 16.16<TEX>${\sim}$</TEX>18.95 kg in all groups. Among these groups, alfalfa-TMFF group was highest(P<0.05). Average milk fat contents showed high levels of 4.06<TEX>${\sim}$</TEX>4.79% and the level was high in order of rape-, grass-, corn-, alfalfa-, rye- and oats-TMFF. Milk protein was highest in forage-TMFF and level of lactose in milk was approximately 4.56% in overall groups. Solid non fat(SNF) and total solid(TS) contents were 8.75% and 12.8%, respectively. However, milk composition was not significantly affected by TMFF.

Effects of Supplemental Dietary Biotin on Performance of Holstein Cows During Early Lactation

This study determined the effects of supplemental dietary biotin (0, 10, or 20 mg/d) on performance of Holstein cows (n=45; 18 primiparous and 27 multiparous). Treatments started at 14 d prepartum and continued until 100 d in milk (DIM). Blood samples were taken at 14 d prepartum, and blood and milk samples were taken at calving, and 30, 60, and 100 DIM. Dry matter intake during lactation was not different across treatments (19.7 kg/d). Milk production linearly increased with biotin supplementation (36.9, 37.8, and 39.7 kg/d for 0, 10, and 20 mg/d of supplemental biotin, respectively). Biotin supplementation did not affect milk fat and true protein percentages or fat yield but linearly increased true protein yield. Supplemental biotin increased concentrations of biotin in plasma and milk at all time points. Concentrations of biotin in plasma and milk (colostrum) at calving were higher than at other time points for cows fed supplemental biotin. In an ancillary experiment, plasma biotin concentrations were not as high when cows were fed 20 mg/d of supplemental biotin for 14 d during the middle of their dry period as when cows were fed 20 mg/d of biotin for the last 14 d of gestation. This suggests that events associated with parturition altered plasma biotin concentrations. Plasma concentrations of glucose, insulin, nonesterified fatty acids, and molar proportions of ruminal volatile fatty acids were not affected by biotin supplementation. Biotin supplementation had no effect on change in body weight or condition score. Supplemental biotin linearly increased milk and protein yields, however, the mode of action that caused these increases was not determined.

Progesterone profiles in postpartum Holstein dairy cows as an aid in the study of retained fetal membranes, pyometra and anestrus

This study was carried out to investigate the utility of enzymeimmunoassay (EIA) - derived progesterone profiles in the investigation of postpartum reproductive abnormalities and the effect of their use on reproductive performance in Holstein cows. Whole milk samples, collected twice weekly from parturition until confirmation of pregnancy or removal from the herd, were assayed for progesterone (P4) concentration using a commercially available microtitre plate EIA. The sensitivity, specificity, precision and accuracy were satisfactory to distinguish cyclic changes of P4 reflecting ovarian activity. The P4 profiles indicated that retained fetal membranes and anestrus were associated with increased mean intervals to first ovulation and first estrus (P < 0.05). The first luteal phase of cows with pyometra was prolonged compared with that of normal herdmates (P < 0.05). Anestrus cows had an increased number of ovulations before first service and before pregnancy (3.9 and 5.9) in comparison with normal herdmates (2.1 and 3.5; P < 0.05). Calving to pregnancy interval was increased above normal (74.8) for pyometra (125.0) and anestrus (152.7) (P < 0.05). Pregnancy rate for anestrus cows (82%) was lower than for normal cows (100%) and more anestrous cows were culled (27%) than normal cows (5%) (P < 0.5). The P4 profiles indicated that the major problem in the herd studied, anestrus (32% incidence rate), was most likely due to the failure to observe estrus rather than acyclicity.

Effect of Feeding Aspergillus oryzae Fermentation Extract or Aspergillus oryzae plus Yeast Culture plus Mineral and Vitamin Supplement on Performance of Holstein Cows During a Complete Lactation

The addition of Aspergillus oryzae fermentation extract (Amaferm®) increased milk flow and mean 3.5% FCM production during the latter stages of the full lactation trial compared with the control group and the Aspergillus oryzae fermentation extract plus yeast culture plus mineral-vitamin supplement (VitaFerm®) group. Based on the differences observed when FCM production was determined for the cows at various stages of lactation, Amaferm apparently had its greatest effect during the early stages of the lactation cycle and subsequent milk production was likely a result of higher initial production. The response difference observed between the Amaferm and VitaFerm treatments could have resulted from the additional minerals provided by the VitaFerm compared with the Amaferm and control groups.

Effect of Dietary Protein and Exogenous Gonadotropin-Releasing Hormone on Circulating Progesterone Concentrations and Performance of Holstein Cows

Sixty-three Holstein cows were used in a 2×2 factorial arrangement of treatments to determine the effects of dietary protein and exogenous gonadotropin-releasing hormone on performance postpartum and on circulating concentrations of progesterone. The experimental diets, 14 or 20% CP (dry basis), were fed from parturition to 14 wk postpartum. Blood serum urea N was elevated in the cows fed the 20% versus 14% CP diet. Feed intake was increased, but yield and composition of milk were not affected by the higher protein diet. Circulating concentrations of progesterone were lower in cows fed 20% than 14% protein on d 12 of both the synchronized and subsequent estrous cycles. Exogenous gonadotropin-releasing hormone administered on d 12 of the preceding estrous cycle did not increase the concentration of progesterone on d 12 of the subsequent estrous cycle. Luteal phase concentrations of progesterone were reduced by high dietary protein, but were not affected by gonadotropin-releasing hormone given on d 12 of the preceding cycle.

Effects of Sixty-Day Milk Yield on Postpartum Breeding Performance in Holstein Cows

The relationship between breeding performance and postpartum milk yield was evaluated using data collected in a prospective field project from 33 New York Holstein herds. Herds selected were enrolled in the New York Dairy Herd Improvement Cooperative program and monthly or biweekly herd health visits from the New York State College of Veterinary Medicine. Factors other than milk yield (e.g., postpartum reproductive disorders, inseminator, housing) that influence breeding performance were controlled in multiple regression analyses. Milk yield had a slight linear antagonistic relationship with conception at first service, services per conception, and days open but not with interval from parturition to first service, interval between first and second services, or interval between second and third services. Services per conception and days open increased by .009 and .6, respectively, for each 100-kg increase in cumulative milk yield during the first 60 d of lactation. Postpartum reproductive disorders, service method (artificial vs. natural), inseminator (farmer vs. technician), and calving interval of the previous lactation had more important relationships than milk yield with measures of breeding performance.

Influence of early estrus, ovulation, and insemination on fertility in postpartum Holstein cows

Our objective was to determine the effects of early estrus and ovulation on subsequent reproductive performance in Holstein cows (n=80) first inseminated after 40 days postpartum. Blood for radioimmunoassayable progesterone was collected twice weekly between calving and day 85 postpartum to determine ovulation frequency. Changes in serum progesterone concentration and visual observation of estrus were used to estimate first and subsequent ovulations and duration of estrous cycles before first service. Reproductive performance was measured by first-service conception rates, days open, and total services per conception. Interval to first ovulation was 19±1 days (X±SE), whereas interval to first detected estrus averaged 45±3 days. Cows had 3±0.1 and 1.6±0.1 estrous cycles that were ovulatory, and 1.5±0.1 and 1.3±0.1 estrous cycles that were ovulatory and involved detected heats through first service and by 40 days postpartum, respectively. Intervals to first service were prolonged when: 1) first ovulations were delayed beyond 4 wk; 2) when first expressed heats were delayed beyond 60 days postpartum; and 3) when first estrous cycles were longer than 24 days. Intervals from calving to conception were extended when cows failed to show estrus before day 60 postpartum and when interval to first service was prolonged. Postpartum fertility was improved (higher frist-service conception rates) when cows had one or two heats by day 40 and when first inseminated before day 60 postpartum. Failure to express estrus was associated with uterine infection, persistent luteal function, and(or) prolonged anovulation. Estrus by day 40 postpartum appeared to be a good indicator of the reproductive status of the dairy herd because fertility and overall reproductive performance was improved by early reestablishment of ovarian cycles and estrous expression.

Relationships Among Type of Parturition, Type of Discharge From Genital Tract, Involution of Cervix, and Subsequent Reproductive Performance in Holstein Cows

Data were from 492 Holstein cows calved between October, 1976, and May, 1977, in eight herds in Michigan. Diameter of the cervix of each cow was estimated by palpation at 8 to 21 days postpartum and again 2 wk later. Parturition and postpartum discharge from the genital tract were classified as normal or abnormal. Size of the cervix between 12 and 26 days postpartum was classified as small, medium, or large within two parity groups. Incidence of abnormal parturition and incidence of abnormal postpartum discharge were 14.1 and 38.0%. Involution of the cervix was affected by parity and type of postpartum discharge. Involution of the cervix occurred sooner postpartum in primiparous than in multiparous cows and sooner postpartum in cows with normal discharge than in cows with abnormal discharge. The greatest difference in cervix diameter between cows with normal or abnormal discharges was 10mm at 3 wk postpartum. Days from parturition to first detected estrus and first service were extended by abnormal postpartum discharge but not by abnormal parturition. First-service conception rate was lower and days from parturition to conception were higher in cows with medium or large cervices compared to cows with small cervices. Type of postpartum discharge and size of cervix early postpartum may be useful for predicting subsequent reproductive performance in dairy cows.

Effect of Summer Weather on Performance of Holstein Cows in Three Stages of Lactation

Energy intake, milk yield, milk fat and rectal temperature of 36 Holstein cows representing three stages of lactation, were examined in relation to air temperature, relative humidity, indices combining these two variables (THI and THC) and wind velocity occurring June to August. Averages for maximum daily temperature, mean daily, THI, and relative humidity were 31C, 26C, 75 and 63%. Values of THI and maximum temperature showed closest relation to cow response. For all stages of lactation, 9% of the variation in milk yield, 13% in milk fat, 5% in feed intake and 65% in rectal temperature were attributable to weather conditions. Rectal temperature and energy intake had the highest correlation with weather on the same day while conditions 2 to 3 days previous were most closely associated with milk yield and milk composition. Changes in feed intake and milk yield depended largely on the stage of lactation. Midlactation cows (100 to 180 days) were most adversely affected; late (180 to 260 days), intermediate, and early (< 100 days) least. Early stage cows consumed the least feed energy but were highest in production indicating they utilized body reserves rapidly to offset the impact of thermal stress. Although weather conditions for the 52 days of study were significantly correlated with milk yield, milk fat percent and energy intake, effects were generally less than reported from studies in heat chambers.