Effect of feeding on reproductive performance in Finnish dairy cows

The effect of 2 types of feeding on the involution of the genital tract and on the fertility was studied in 79 Finnish dairy cows on a research farm. The cows were fed twice a day with home-produced feed in accordance with the Finnish feeding standard. The cows were divided according to the type of feed into a hay-urea group and a silage group. The cows were examined clinically by rectal palpation 3 times a week during 8 weeks postpartum. The time required for the complete involution of uterus and cervix was recorded. The cows in the silage group had a significantly longer time in uterine involution, a lower fertility rate at first insemination and a longer interval from calving to conception than those in the hay-urea group. The pregnancy rate in the first insemination was in the hay-urea group 91% and in the silage group 57%. The interval between calving and the first insemination was shorter in the hay-urea group than in the silage group: 71.4 +/- 10.6 and 74.0 +/- 10.3 days, respectively. The interval between calving and conception was in the hay-urea group significantly (p less than 0.01) shorter than in the silage group; 74.8 +/- 15.1 and 89.5 +/- 24.4 days, respectively.     

Effects of prostaglandin on the reproductive performance of dairy cows

A single injection of a synthetic analogue of prostaglandin F2 alpha (fenprostalene; Syntex) on the day of calving or between days 14 and 21 after calving did not affect the calving to first service interval, the number of services per conception or the conception rate of dairy cows. In a second trial, cows calved more than 45 days were injected once weekly with prostaglandin F2 alpha (dinoprost; Upjohn) or fenprostalene until served at the first detected oestrus. The calving to first service interval and the conception rate were not affected. Following injection of either prostaglandin, the spread in the pattern of onset of oestrus and the range in the proportion of cows (75 to 98 per cent) seen in oestrus within seven days were similar. This variation in the time of onset of oestrus after the administration of prostaglandin precludes limiting oestrus detection to four or five days per week, and is a major limitation to the use of prostaglandins in breeding programmes in dairy cows.     

Effect of extruded linseed on productive and reproductive performance of lactating dairy cows

A total of 356 early lactation multiparous Holstein cows were used in a randomized complete block design to determine the effects of feeding extruded linseed on milk production and composition, and reproductive performance. Forty of these cows were randomly selected to study the effects of extruded linseed on milk fatty acid (FA) profile, individual feed intake and prostaglandin secretion. Cows were fed a 40:60 forage to concentrate ratio diet (17.9% CP, 27.7% NDF and 6.0% EE) ad libitum that was similar in composition between treatments except for the protein supplements that differed and were control (CTR: 4.9% extruded soybean) and linseed (LIN: 5.5% extruded linseed). Individual DM intake measured at 40 (23.0 kg/d) and 90 (24.2 kg/d) days in milk, and milk yield (45.0 kg/d) were not affected by treatment, but the lower (P < 0.05) milk fat percentage in cows fed LIN (2.65%) compared with CTR (2.86%) resulted in lower (P < 0.05) 4.0% fat-corrected milk yield for cows fed LIN (35.4 kg/d) compared with CTR (37.7 kg/d). Milk protein content was higher (P < 0.05) in LIN (3.04%) than in CTR (3.00%). The concentration of saturated FA was lower (P < 0.05) in milk fat from LIN (56.2%) compared with CTR (60.2%). Monounsaturated FA (35.7 vs. 32.7%) and polyunsaturated FA (8.0 vs. 6.9%) were higher in LIN (P < 0.05) than in CTR. Supplementation with LIN also increased (P < 0.05) the proportion of vaccenic acid (2.21 vs. 1.55%), total conjugated linoleic acid (0.91 vs. 0.72%) and n-3 FA (1.21 vs. 0.54%) in milk compared with CTR. Plasma concentrations of prostaglandin metabolite were numerically lower in LIN (106 pg/ml) compared with CTR (120 pg/ml) (P = 0.16) but reproductive performance was similar between treatments. In summary, extruded linseed reduced milk fat percentage and 4.0% fat-corrected milk yield and increased milk protein percentage and the content of healthy FA in milk without modifying DM intake, milk yield and reproductive performance.     

亚临床酮病对泌乳早期奶牛繁殖性能的影响

为探究围产期亚临床酮病与泌乳奶牛繁殖性能及卵泡发育之间的关系,本试验选择了黑龙江省某大型集约化牛场开展试验,根据产后血酮水平确定亚临床酮病组和健康组奶牛共80头,该牛场亚临床酮病发生率为71%;两组奶牛跟踪到产后50 d进行直肠检查和B超检查了解卵泡发育状况,并记录繁殖性能数据。结果显示:与健康组奶牛相比,亚临床酮病组奶牛产后首次发情天数延长10 d,产后60 d内发情次数少0.58次;产后50 d子宫复旧不全高15%,与亚临床酮病呈显著正相关(R^2=8.74);产后60 d卵泡直径小3 mm(P<0.05)。结论:该牛场奶牛亚临床酮病发病率较高,是引起奶牛产后繁殖障碍的风险因素,也是造成卵泡发育受阻的不良因素,会导致奶牛繁殖力下降。     

Trends in the reproductive performance of Holstein dairy cows in Iran

The study was undertaken to determine the trends in the reproductive performance of Holstein dairy cows in Iran during 1994 to 2008. Reproductive performance data for 528,034 lactations of 246,132 cows in 1,822 Holstein dairy herds of Iran were used. The potential effect of calving season, herd, parity, calving year, as well as herd size and 305-day milk production on reproductive performance traits was investigated using multiple regression models. The least squares means of age at first calving decreased by 3.1 (±0.06) days per year from 806.5 (±96.3) days in 1994 to 788 (±89.9) days in 2008. The least squares means of calving interval increased 1.02 (±0.03) days per year from 394.1 (±65) days in 1994 to 413.2 (±81) days in 2008. Greater 305-day milk production was associated with an average increase of 6.55 (±0.08) days in calving interval per 1,000-kg increase in milk yield. Larger herd size was associated with an average decrease of 0.22 (±0.02) days in calving interval per 50 cows per herd. The mean number of days dry was 88.6 (±51.3) days and increased by 0.82 (±0.02) days per year. In conclusion, reproductive performance in Holstein dairy herds has generally decreased, whereas herd size and milk production have increased over time. Producers may make significant improvements in herd reproduction by reviewing management strategies including the sire selection, reproductive management, inseminator training and techniques, and improved estrous detection. Moreover, it may be advisable for the fertility traits to be included in the genetic selection indices to reduce the rate of reproductive decline.     

Effect of intrauterine antibiotic treatment on reproductive performance of dairy cows following periparturient disease

AIMS: To quantify the effect of treating lactating dairy cows that had histories of periparturient disorders or disease with a single intrauterine infusion of 0.5 g cephapirin, 3-6 weeks prior to the start of the seasonal breeding period. METHODS: Cows (n=690) from spring-calving dairy herds (n=22) were enrolled in a prospective case-control study if they had a history of dystocia, a dead calf at calving or within 24 h of calving, retained foetal membranes (RFM), metabolic disease, twins or a vulval discharge 13 days postpartum. Cows were blocked by age, periparturient condition and calving date, and randomly assigned to be either treated with 0.5 g of cephapirin by intrauterine infusion, or left as untreated controls. Treatment occurred 24-42 days before the planned start of mating (PSM) within each herd. In addition, the reproductive tracts of 91 cows from 4 herds were examined using a vaginal speculum and rectal palpation and cervical-os discharge was scored on a scale from 0 (nil) to 3 (purulent). RESULTS: Overall, more treated cows were retained in the trial herds until pregnancy testing than control cows (p0.05). Average 28-day submission rate was higher (93.1% vs 87.1%; p0.05) and PSM-to-first-service interval was shorter (9+/-1 vs 11+/-1 days; p0.05) in treated than control cows. The percentage of cows not pregnant at the end of the mating period was not affected by treatment overall. However, amongst cows diagnosed with RFM, a dead calf, or vulval discharge, pregnancy rates 28 and 56 days after PSM were higher for treated than control cows (p0.05). Cows with a purulent cervical-os discharge had lower 28-day submission rates (p0.01), lower 28-day pregnancy rates (p0.05) and higher non-pregnant rates at the end of mating than cows with nil or mucoid cervical-os discharges. CONCLUSIONS: Intrauterine treatment with 0.5 g cephapirin improved reproductive performance of dairy cattle, especially those that had a history of RFM, a calf dead at calving or within 24 h of calving, or a vulval discharge.     

日粮中添加藜麦秸秆对奶牛生产性能和血清生化指标的影响

为研究日粮中添加藜麦秸秆对奶牛生产性能和血清生化指标的影响,试验根据胎次相同,产犊时间、体重、产奶量相近的原则,选择16头中国荷斯坦奶牛作为试验牛。采用单因子随机试验设计,随机分为4组,每组4头牛,分别饲喂4种不同比例藜麦秸秆的全混合日粮(TMR)。藜麦秸秆的干物质(DM)添加比例分别为0%(Ⅰ组),5%(Ⅱ组),10%(Ⅲ组),15%(Ⅳ组)。预试期10d,正式期60d。结果表明:试验Ⅱ、Ⅲ组的产奶量、4%标准乳产量显著高于试验Ⅰ组(P<0.05),试验Ⅱ、Ⅲ组的产奶量分别比试验Ⅰ组高6.58%和6.87%,试验Ⅱ、Ⅲ组的4%标准乳分别比试验Ⅰ组高5.37%和10.61%;试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组的乳脂率、乳糖率、乳蛋白率和乳总固形物差异均不显著(P>0.05);试验Ⅰ、Ⅱ、Ⅲ组和Ⅳ组的粗蛋白质(CP)、中性洗涤纤维(NDF)、酸性洗涤纤维(ADF)的表观消化率差异不显著(P>0.05);试验Ⅰ、Ⅱ、Ⅲ、Ⅳ组葡萄糖、甘油三酯、高密度脂蛋白、低密度脂蛋白、尿素氮、总蛋白、白蛋白、球蛋白、谷丙转氨酶、谷草转氨酶和碱性磷酸酶差异均不显著(P>0.05)。综上所述,奶牛日粮中添加藜麦秸秆能提高其产奶量,对血清生化指标无不利影响。     

Effect of E. coli ectotoxin on calcium and phosphate concentration in serum of dairy cows

The injection of E. coli ectotoxin into eight healthy cows of the SRB breed induced a significant hypocalcemia and hypophosphatemia. A clinical profile similar to that normally seen in paresis puerperalis was also observed. These results confirm earlier observations that toxaemia can give rise to paralytic symptoms.     

Effect of timing of artificial insemination after synchronization of ovulation on reproductive performance in Holstein dairy cows

The objective of this study was to determine the effect of timing of artificial insemination on pregnancy rates, calving rates, abortion rates, twinning rates, and calf gender ratio after synchronization of ovulation with Ovsynch protocol in Holstein dairy cows. The ovulation of 219 lactating Holstein dairy cows was synchronized using the Ovsynch protocol. Therefore, cows received an injection of GnRH followed by an injection of prostaglandin F_2α 7 days later and a second treatment with GnRH 2 days later. Cows were artificially inseminated at 0, 12, or 24 h after the second injection of GnRH. Reproductive performance did not differ between cows inseminated at 0 h (n?=?82), 12 h (n?=?66), or 24 h (n?=?71) after the last injection of GnRH (pregnancy rate: 0 h 48 %, 12 h 47 %, 24 h 52 %; abortion rate: 0 h 5 %, 12 h 0 %, 24 h 11 %; calving rate: 0 h 43 %, 12 h 47 %, 24 h 41 %; twinning rate: 0 h 2 %, 12 h 0 %, 24 h 0 %; calf gender ratio (F/M): 0 h 61:39 %, 12 h 48:52 %, 24 h 39:61 %; P?>?0.05). Pregnancy rates for cows inseminated in postpartum times of 50–75, 76–100, and >100 days within the first and ≥3 parities were statistically similar (P?>?0.05), but pregnancy rates for cows inseminated at different postpartum times of 50–75, 76–100, and >100 days within the second parity were different (P?<?0.01). In general, pregnancy rates of cows inseminated at different postpartum times (P?<?0.01) and parities (P?<?0.001) differed. The findings of the current study showed that rates of pregnancy, abortion, calving, and twinning of Holstein dairy cows subjected to artificial insemination at different times after synchronization were similar. These results also indicate that the timing of artificial insemination after synchronization did not influence calf gender ratio. Furthermore, pregnancy rates of Holstein dairy cows inseminated after synchronization were significantly influenced by postpartum time and parity number.     

香兰素对泌乳前期奶牛产奶性能及血清生化指标的影响

本试验旨在研究香兰素对奶牛干物质采食量、产奶量、乳成分及血清生化指标的影响,为香兰素在奶牛生产上的开发应用提供科学依据。选取40头健康的荷斯坦奶牛进行配对,随机分为对照组和试验组,每组20头,在相同的条件下饲养。对照组饲喂牛场全混合日粮,试验组在对照组日粮基础上添加10 g/d香兰素,预试期7 d,试验期70 d。结果表明:日粮添加10 g/d香兰素对奶牛泌乳前期的干物质采食量、产奶性能无显著影响(P0.05);日粮中添加10 g/d香兰素对泌乳前期奶牛的乳成分无显著影响(P0.05);日粮中添加10 g/d香兰素对血清生化指标无显著影响(P0.05)。得出结论:在日粮中添加10 g/d香兰素对泌乳前期奶牛的生产性能及血清生化指标无显著影响。     

Gonadotropin-releasing hormone improves reproductive performance of dairy cows with slow involution of the reproductive tract

Eighty multiparous Holstein cows were assigned randomly at calving to receive either 100 microg of GnRH or saline 13 or 14 d postpartum (PP). From 4 to 28 d PP the cows' reproductive organs were palpated weekly per rectum, and cows were subclassified within each group as undergoing slow (delayed) cervical and uterine involution (abnormal) or as normal cows. Last milk obtained after removing the milking machine was assayed for progesterone 3 times a week for 120 d PP. Fourteen of the 80 cows were removed from the experiment because of culling or various veterinary treatments of pathologic conditions that could confound analysis of the GnRH treatment effects. As expected, the treatment of normal cows with GnRH had no significant effects on the first estrus or the first estrous cycle PP, on services per conception, days open, or any other reproductive trait measured. However, in the abnormal group of cows receiving saline, first rebreeding after calving was delayed (81 vs. 67 d), fewer were pregnant by 105 d PP (23 vs. 64%), and number of days open was greater (121 vs. 87 d) compared with those receiving GnRH; all were significant (P<.05). Treated abnormal cows were equivalent to the control normal cows. Thus, GnRH given 13 to 14 d PP to cows characterized as undergoing slow involution of the reproductive system, but with no other clinical problems, seems to assist in promoting rapid normal reproductive function. Subsequent losses due to culling were greatly reduced.     

Effect of postpartum live weight loss on reproductive functions in dairy cows

Postpartum loss of live weight in dairy cows and its association with reproductive functions were studied in a total of 84 (42 Ayrshire and 42 Friesian) cows. The cows were divided according to type of feed into 2 groups of equal size: a hay-urea group and a silage group. The duration of the study was 3 years. All 84 cows were followed during their first postpartum period, 63 during 2 and 57 during 3 consecutive postpartum periods.The resumption of ovarian function was monitored by means of a thrice weekly milk progesterone assay between calving and the first insemination.Live weight changes during the first 30 and 60 days post partum were compared between the 2 breeds and the 2 feed groups.After the second parturition, the mean live weight loss within 30 and 60 days post partum was roughly twice as high (11%) as after the first (4%) and third (6%) carvings. Breed had no significant effect on weight change. The cows in the silage group lost slightly more weight after each parturition than those in the hay-urea group. Low, but statistically significant correlations were noted between weight loss post partum and reproductive functions. The interval from calving to onset of the first visible oestrus was 6 days longer, and to pregnancy 8 days longer in cows which lost more than 10% live weight within 60 days post partum than in those which lost less than 10% (p<0.05). The fertility rate at first insemination (53.1%) was lower in cows which lost more than 10% weight than in those (74.4%) which lost less than 10% (p<0.01). Heat detection rate was not affected by weight loss.     

Metabolic changes in early lactation and impaired reproductive performance in dairy cows

This review addresses the suggestion that the decline in dairy reproductive performance, as increasingly observed these days, may be due to a hampered process of metabolic adaptation in early lactating cows. In our opinion, adaptation to the negative energy balance is a gradual process. Because almost all cows do adapt in the long run, it is not possible to classify animals as adapted or non-adapted. The use of risk factors is more appropriate in this case and is discussed in this review. Among them are the body condition score and its derivatives, feed intake, the calculated negative energy balance, and metabolic parameters like the plasma concentration of insulin or the triacylglycerol content in the liver. Moreover, factors that play a role in the link between declined reproductive performance and the metabolic situation of the cow during the early lactating period are discussed. Among these are insulin, insulin-like growth factors, leptin, neuropeptide Y, non-esterified fatty acids, thyro?d hormones, urea, and ammonia.     

Effect of yeast culture on milk production and metabolic and reproductive performance of early lactation dairy cows

Background

The main objective of this study was to estimate the effect of supplementation with Saccaromyces cerevisiae (SC) (Yea-Sacc^® 1026) on milk production, metabolic parameters and the resumption of ovarian activity in early lactation dairy cows.

Methods

The experiment was conducted during 2005/2006 in a commercial tied-house farm with an average of 200 milking Estonian Holstein Friesian cows. The late pregnant multiparous cows (n = 46) were randomly divided into two groups; one group received 10 g yeast culture from two weeks before to 14 weeks after calving. The groups were fed a total mixed ration with silages and concentrates. Milk recording data and blood samples for plasma metabolites were taken. Resumption of luteal activity was determined using milk progesterone (P₄) measurements. Uterine bacteriology and ovarian ultrasonography (US) were performed and body condition scores (BCS) and clinical disease occurrences were recorded. For analysis, the statistical software Stata 9.2 and R were used to compute Cox proportional hazard and linear mixed models.

Results

The average milk production per cow did not differ between the groups (32.7 ± 6.4 vs 30.7 ± 5.3 kg/day in the SC and control groups respectively), but the production of milk fat (P < 0.001) and milk protein (P < 0.001) were higher in the SC group. There was no effect of treatment on BCS. The analysis of energy-related metabolites in early lactation showed no significant differences between the groups. In both groups higher levels of β-hydroxybutyrate (BHB) appeared from days 14 to 28 after parturition and the concentration of non-esterfied fatty acid (NEFA) was higher from days 1–7 post partum (PP). According to US and P₄ results, all cows in both groups ovulated during the experimental period. The resumption of ovarian activity (first ovulations) and time required for elimination of bacteria from the uterus did not differ between the groups.

Conclusion

Supplementation with SC had an effect on milk protein and fat production, but did not influence the milk yield. No effects on PP metabolic status, bacterial elimination from the uterus nor the resumption of ovarian activity were found.     

Effects of work on reproductive and productive performance of crossbred dairy cows in the Ethiopian highlands

Summary An investigation was made at the International Livestock Centre for Africa (ILCA), into the possibility of using cows in land cultivation as a means of reducing the dependency of smallholder farmers in the Ethiopian highlands on draught oxen power, a resource which is in short supply during the peak of the cultivation season and usually leads to late planting and poor harvest. A total of 32 crossbred cows (1/2 Boran −1/2 Friesian) were used in an experiment to determine whether cows could be used to cultivate an average smallholder farm of 2·5 ha and to assess the effects of work on reproductive and productive performance; 16 served as a control group and were milked, but not worked while the other 16 were milked in addition to providing draught power for cultivation. Draught cows were provided with extra feed and consumed 7% and 21% more hay and concentrate respectively than non-draught cows during a two-lactation cycle. After the end of the second lactation there were no significant differences between draught and non-draught animals for milk production (1,713±57·4 compared with [vs] 1,857±48·1 kg), lactation length (291±20·4 vs 277±18·0 days), calf birth weight (29·6±1·0 vs 29·3±1·0 kg), number of days open (77±14·1 vs 83±12·9), calving interval (355±14·5 vs 358±13·2 days), gestation length (278±1·6 vs 274±1·4 days) and number of services per conception (1·21 vs 1·64). The number of hours worked by each pair of crossbred cows was sufficient to cultivate the average smallholder farm of 2·5 ha. However, the work done was spread over a longer time than that required by the smallholder farmer to cultivate 2·5 ha. It was concluded that at low levels of work and with improved feeding management, draught or traction does not have adverse effects on reproductive and productive performance of crossbred dairy cows.

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Resumen Se realizó una investigación en el Centro Internacional de Ganadería para Africa (ILCA), sobre el uso de vacas en el cultivo de la tierra en lugar de bueyes, los cuales son escasos en la época pico de labranza, lo cual conlleva a que se siembre tarde con la consecuente baja producción. Se utilizaron para el estudio 32 vacas media sangre Borán/Holstein, para determinar si éstas podían servir para las labores de cultivo de peque?as fincas de 2·5 hectáreas, sin menoscabo de la producción y reproducción. Dieciseis sirvieron como controles, las que se orde?aron pero no se utilizaron en labores de cultivo. Las vacas que se utilizaron para trabajar, recibieron alimentación extra, consumiendo 7% y 21% más heno y concentrado, durante dos ciclos de lactación.

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Résumé Une enquête a été réalisée à l'ILCA/CIPEA sur la possibilité d'utiliser des vaches pour cultiver la terre, en vue de réduire, la dépendance des petits fermiers des Hautes Terres éthiopiennes vis à vis des disponibilités en boeufs de trait. Cette ressource est en effet limitée pendant la pointe de la saison des cultures, et ceci a pour conséquences des plantations tardives et une moisson médiocre. Un total de 32 vaches croisées (1/2 Boran −1/2 Frison) ont été utilisées pour essayer de déterminer si ces animaux pouvaient être employés pour les travaux de cultures sur une ferme moyenne de 2,5 ha de superficie représentative d'une petite propriété et pour mesurer les effects du travail sur les performances de production laitière et de reproduction. Seize ont constitué un lot témoin. Elles ont été traites mais, n'ont pas travaillé tandis que 16 autres ont été traites tout en apportant leur force de travail pour la culture. Les vaches de trait ont re?u une alimentation complémentaire et ont respectivement consommé 7% et 21% de foin et de concentré de plus que les vaches non utilisées pour la traction pendant un cycle de 2 lactations.

     

The effects of progesterone treatment following artificial insemination on the reproductive performance of dairy cows

The objective of this study was to examine the effects of increasing circulating progesterone in multiparous Holstein cows, using an intravaginal progesterone implant between days 3 and 7 following fixed-time artificial insemination (FTAI). The animals were randomly assigned into two groups: (1) treatment group and (2) control (no treatment). The experiment took place during periods of high and mild temperatures. Pregnancy rates were evaluated by ultrasound at 30 and 60 days after FTAI; embryonic and fetal mortality rates were also evaluated on these dates. The temperature and humidity index on the day of FTAI were different (P?<?0.05) during the times of interest, but it did not affect conception rates. Neither the conception rates at days 30 and 60 nor the embryonic and fetal mortality rates differed between the groups during either the high- or mild-temperature periods (P?>?0.05). Throughout the experimental period, the serum progesterone concentration was higher in the treatment group than in the control (P?<?0.05). We conclude that the intravaginal progesterone implant inserted from days 3 to 7 following FTAI had no effect on conception rates at days 30 and 60 or on embryonic or fetal mortality rates but enhances the serum progesterone concentrations following treatment in multiparous Holstein cows during high- and mild-temperature periods.     

Effect of delayed colostrum collection on colostral IgG concentration in dairy cows

OBJECTIVE: To determine the effect of timing of first-milking colostrum collection on colostral IgG concentration. DESIGN: Prospective study. ANIMALS: 13 healthy Holstein cows. PROCEDURES: All calvings were observed. After parturition, calves were not allowed to suckle and were separated from the dam. Colostrum was collected from a single randomly selected quarter at 2, 6, 10, and 14 hours after parturition until all 4 quarters were sampled. Colostral IgG concentration was determined via radial immunodiffusion. RESULTS: Mean colostral IgG concentration was 113, 94, 82, and 76 g/L at 2, 6, 10, and 14 hours after calving, respectively. Colostrum collected 6, 10, and 14 hours after calving had significantly lower IgG concentrations than did colostrum collected 2 hours after calving. Mean colostral IgG concentration at 14 hours after calving was significantly lower than that at 6 hours after calving. Cows in their third or greater lactation had mean colostral IgG concentrations 2 hours after calving (132 g/L) that were greater than the first and second lactation cows (mean, 95 and 100 g/L, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that early or immediate colostrum collection from dairy cows will maximize colostral IgG concentration. Adjustment of routine dairy farm management procedures may be required to maximize colostrum quality and minimize prevalence of failure of passive transfer in dairy calves.     

Effects of periparturient diseases and conditions on the reproductive performance of New Zealand dairy cows

AIM: To determine the effect of retained foetal membranes (RFM), periparturient recumbency, calf mortality, dystocia, twin births and induction of parturition on submission and pregnancy rates of pasture-fed, seasonally-calving dairy cows in New Zealand. METHODS: Data were retrospectively collected for 2652 cows from 11 herds on the occurrence of periparturient diseases and condition, calving date, age and treatment for anoestrus prior to the planned start of mating (PSM). The effects of each disease or condition on submission and pregnancy rate by 28 days after PSM, final pregnancy rate, and the proportion of cows that conceived more than 50 days after PSM were examined using separate logistic regression models. Results are expressed as odds ratios (OR). Additionally, the effect of each disease or condition on the interval from PSM to conception was examined using survival analysis. Age, herd and late calving (i.e. cows calved < or =40 days before PSM) were included as factors in the models examined. RESULTS: Induction of parturition increased the risk of RFM (OR=3.3, p<0.01). The 28-day submission rate was affected by age and herd but not by any of the periparturient conditions examined. The 28-day pregnancy rate was reduced by RFM (OR=0.04, p<0.05), induction of parturition (OR=0.67, p<0.01), assisted calving (OR=0.61, p<0.01), late calving (OR=0.55, p<0.05) and anoestrus (OR=0.27, p<0.05). The final pregnancy rate was reduced by RFM (OR=0.013, p<0.01), induction (OR=0.25, p<0.05), assisted calving (OR=0.30, p<0.005) and anoestrus (OR=0.32, p<0.05), and was increased if the cow was submitted for mating within 28 days after PSM (OR=2.72, p<0.05). Effects of recumbency and twinning were not significant in any of the models. CONCLUSIONS: Cows that had had RFM or were assisted, induced or late to calve, had significantly lower pregnancy rates or took longer to conceive than unaffected herd-mates. CLINICAL RELEVANCE: Intervention programs aimed at the examination and treatment of cows with periparturient conditions may improve the reproductive performance of New Zealand dairy herds. Investigations of poor reproductive performance of a herd should include analysis of the prevalence and effects of periparturient diseases and conditions.