A note on the effect of vasectomised rams and short-term exposures to entire rams prior to the breeding period on the reproductive performance of ewe lambs

The aims of this study were to examine the effects of exposing Romney ewe lambs (8–9 months of age) to vasectomised rams across three studies in the February–March period and to determine the influence of body condition score (CS) in two of the studies on their reproductive performance. In all studies, ewe lambs exposed to vasectomised rams had greater (P < 0.05) conception rates to the first 17 days of breeding by 6–12 percentage points. However, Studies 2 and 3 indicated that exposing ewe lambs to vasectomised rams did not increase (P > 0.05) the percentage of ewe lambs conceiving over a 34-day breeding period, nor did it increase the number of fetuses per ewe lamb presented for breeding. The results of Study 1 suggest that there is a limit to how early in the year ewe lambs can be exposed to vasectomised rams. In Study 2, a greater (P < 0.05) percentage of Teased CS 2.0 or 2.5+ ewe lambs conceived during the first 17 days of breeding than those which were Unteased. This effect was not observed (P > 0.05) in CS 1.5 ewe lambs. In Study 3, a greater (P < 0.05) percentage of CS 2.5+ ewe lambs conceived over the 34-day breeding period than ewe lambs of lower CS. In Studies 2 and 3, ewe lambs with a CS of 2.5+ had a greater (P < 0.05) number of fetuses per ewe lamb presented for breeding than CS 1.5 ewe lambs. In conclusion, exposing ewe lambs to vasectomised rams in the late February or March period increased the proportion of ewe lambs successfully bred in the first 17 days of breeding. Further achieving higher CS and heavier liveweights of ewe lambs at breeding should result in improved reproductive performance.

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A note on the effects of 72-hour calf removal and/or bull exposure upon post-partum reproductive performance of angus cows

Animal Science ◽

10.1017/s0003356100004621 ◽

1990 ◽

Vol 50 (1) ◽

pp. 202-206 ◽

Cited By ~ 4

Author(s):

J. J. Bonavera ◽

G. C. S. Schiersmann ◽

R. H. Alberio ◽

J. Mestre

Keyword(s):

Body Condition ◽

Reproductive Performance ◽

Post Partum ◽

Early Summer ◽

Breeding Period ◽

Short Term ◽

Blood Samples ◽

Good Body Condition ◽

Calf Removal ◽

Natural Service

The objective of the present study was to determine whether short-term calf removal (SCR) and/or bull exposure (BE) could improve post-partum reproductive performance. The trial was conducted during the spring and early summer when forage availability was optimum. Sixty-four Angus multiparous cows in good body condition were allotted according to a 2 × 2 factorial design involving SCR and BE. At 33 days post partum calves were removed for 72 h from the SCR and SCR + BE groups, and a vasectomized bull was introduced to the BE and SCR + BE groups and remained with the cows until the end of the experiment. Oestrous detection was performed daily based only on the homosexual behaviour of the cows. Cows were bred by natural service by two fertile bulls. Blood samples for progesterone analysis were collected alternatively every 3 and 4 days from 26 to 120 days post partum. There were no significant differences (P > 0·05) among groups in the ovulation, oestrus, and pregnancy rates during the breeding period, in conception rates, nor in the intervals from calving to first ovulation, to first oestrus, and to conception. Under the conditions of this experiment 72 h calf removal and/or bull exposure did not improve post-partum reproductive performance.

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Proportion of rams and the condition of ewe lambs at joining influences their breeding performance

Animal Production Science ◽

10.1071/an09178 ◽

2010 ◽

Vol 50 (6) ◽

pp. 454 ◽

Cited By ~ 15

Author(s):

P. R. Kenyon ◽

S. T. Morris ◽

D. M. West

Keyword(s):

Reproductive Performance ◽

Pregnancy Rates ◽

Breeding Period ◽

Breeding Performance ◽

Ewe Lambs ◽

Condition Score ◽

Ewe Lamb ◽

In Pregnancy

The aim of the present study was to examine the effects of ram : ewe lamb ratio and condition score on the reproductive performance of ewe lambs. In the 2007 study, ewe lambs were bred with rams, at ram : ewe lamb ratios of 1 : 30, 1 : 50, 1 : 75 or 1 : 100. In the 2008 study, ewe lambs were bred at ratios of 1 : 31, 1 : 50, 1 : 75 or 1 : 100. Ewe lambs were bred over two 17-day periods. In both studies, ewe lambs bred in the first 17 days of breeding only were heavier (P < 0.05) than those bred in the second 17-day period only, and those ewe lambs diagnosed as twin-bearing were heavier (P < 0.05) than their single-bearing counterparts. Ewe lambs with a condition score of 2.5 or greater were more likely (P < 0.05) to be bred, and be pregnant, in the first 17 days of breeding than those of condition score 1.5 or 2.0. Over the entire 34-day breeding period, ewe lambs with a condition score of 2.5 or greater had higher (P < 0.05) pregnancy rates than those with a condition score of 2.0, which in turn had higher rates than those of 1.5. In the 2007 study, after 34 days of breeding, there were no differences (P > 0.05) in pregnancy rates among the different ram : ewe lamb ratios. While in the 2008 study, pregnancy rates after 34 days were greater (P < 0.05) in the 1 : 50 compared with both the 1 : 75 and 1 : 100 treatments. Pregnancy rates of 1 : 31 ewe lambs were greater (P < 0.05) than those of 1 : 75 ewe lambs. In the 2007 study, pregnancy rates of ewe lambs to the first 17 days of breeding were greater (P < 0.05) for those bred at a ratio of 1 : 75 than for those bred at 1 : 50, and tended to be greater (P = 0.08) than for those bred at 1 : 100. In addition, those bred at a ratio of 1 : 30 tended to have higher pregnancy rates (P = 0.07) than those bred at 1 : 50. While in the 2008 study, pregnancy rates to the first 17 days of breeding were greatest (P < 0.05) in the 1 : 31 and 1 : 50 treatments groups. In conclusion, the results of the present study indicate that achieving greater liveweights and higher condition scores of ewe lambs at breeding will increase the proportion pregnant, especially early in the breeding period. The data also suggest, in combination with the results of previous research, that farmers should consider utilising ram : ewe lamb ratios lower than 1 : 100, although further studies are warranted.

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Behaviour and reproductive performance of Nigerian native chickens subjected to different mating ratios for a short term

Reproduction in Domestic Animals ◽

10.1111/rda.13653 ◽

2020 ◽

Vol 55 (5) ◽

pp. 567-573

Author(s):

Oluwaseun Serah Iyasere ◽

David Oluwatowo Adeuyi ◽

Rasheed Adebayo Alade ◽

Samuel Olutunde Durosaro ◽

Mathew Wheto ◽

...

Keyword(s):

Reproductive Performance ◽

Short Term ◽

Native Chickens

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Live Weight Changes and Their Relationship with the Ovarian Status of Maiden Fat-Tailed Barbarine Ewes

Journal of Agricultural and Marine Sciences [JAMS] ◽

10.24200/jams.vol15iss0pp41-46 ◽

2010 ◽

Vol 15 ◽

pp. 41

Author(s):

Imēne Ben Salem ◽

Mourad Rekik ◽

Mohammed Ben Hamouda ◽

Narjess Lassoued

Keyword(s):

Weight Loss ◽

Reproductive Performance ◽

Ovarian Function ◽

Live Weight ◽

Weight Changes ◽

Ewe Lambs ◽

Ovarian Status ◽

Weight Variation ◽

Igf I ◽

Semi Arid

The current study assessed the effect of the pattern of live weight change on the ovarian function of maiden Barbarine ewes at approximately 1 year of age. For this purpose, a total of 171 weaned ewe lambs (mean live weight ± s.d. 34.7±3.07 kg and mean age ± SD 196±10 days at weaning) were selected for the experiment. Adjustment of live weight variation was used. Based on the slope of the curve, animals were grouped into three classes LWCI (n=46), LWCII (n=91) and LWCIII (n=34) with live weight loss being highest in LWCI and lowest in LWCIII. Following laparoscopy at 13 months of age, the proportion of ewe lambs found cycling in LWCIII (85.3%) was higher in comparison to animals in LWCI (43.4%; P<0.001) and tended to be superior to those in LWCII (61.5%; P<0.05). Following synchronisation with progestagen of the females found cycling, levels of plasma IGF-I concentrations between 6 and 42 hrs after removal of sponges were not significantly different between the three classes of live weight, and respectively averaged 94.2, 90.8 and 89.8 µg/l for LWCI, LWCII and LWCIII females. Levels of estradiol were also not significantly different between the three groups (0.73, 0.70 and 0.67 pg/ml for LWCI, LWCII and LWCIII ewe lambs, respectively). It was concluded that, in low input systems of semi-arid and arid Tunisia, mating ewe lambs at the approximate age of 1 year is likely to lead to depressed reproductive performance particularly when the summer live weight-loss is elevated.

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Associations between early lactation milk protein concentrations and the intervals to calving for Holstein cows of differing parity

Animal Production Science ◽

10.1071/an15777 ◽

2017 ◽

Vol 57 (10) ◽

pp. 2100 ◽

Cited By ~ 3

Author(s):

Jack Fahey ◽

John M. Morton ◽

Martin J. Auldist ◽

Keith L. Macmillan

Keyword(s):

Dairy Cows ◽

Reproductive Performance ◽

Milk Protein ◽

Holstein Cows ◽

Breeding Period ◽

Gestation Length ◽

Calving Interval ◽

Early Lactation ◽

Average Interval ◽

Lactating Dairy Cows

High milk protein concentrations (MP%) have been positively associated with the reproductive performance of lactating dairy cows. No studies have measured the effects of this association on subsequent calving dates in multiparous cows, nor assessed whether the underlying causal mechanisms are present in nulliparous heifers. Holstein cows (primiparous = 918; multiparous = 4242) were selected from herds that had seasonally concentrated calving patterns resulting from seasonally restricted breeding periods. In seasonally calving herds, the date of a herd’s planned start of calving (PSC date) is the average gestation length of 282 days after the date that the preceding breeding period commenced, so that the interval from the herd’s PSC date to each cow’s actual calving date (PSC-to-calving interval) primarily reflects the time to conception from the start of the breeding period in the previous year. This measure was used to compare associations between the average MP% during the first 120 days of lactation and time to the calving that initiated that lactation in primiparous and multiparous cows. Early lactation MP% was negatively associated with PSC-to-calving interval. A 1% difference in MP% was associated with an 8-day difference in the average PSC-to-calving interval in primiparous cows and a 31–35-day difference in the average interval in multiparous cows. The observed associations between early lactation MP% and PSC-to-calving interval are likely to involve determinants present during a cow’s breeding period that affect the probability of conception. Some of these determinants are not restricted to early lactation as the association between MP% and PSC-to-calving interval in primiparous cows is a reflection of the reproductive performance in nulliparous heifers at ~15 months of age.

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13 THE RELATIONSHIP BETWEEN EARLIER POSTPARTUM CYCLICITY AND SUBSEQUENT REPRODUCTIVE PERFORMANCE IN DAIRY COWS: A FIELD TRIAL

Reproduction Fertility and Development ◽

10.1071/rdv23n1ab13 ◽

2011 ◽

Vol 23 (1) ◽

pp. 113

Author(s):

I. H. Kim ◽

H. C. Lee ◽

H. G. Kang

Keyword(s):

Dairy Cows ◽

Body Condition ◽

Reproductive Performance ◽

Body Condition Score ◽

Post Partum ◽

Management Program ◽

Breeding Period ◽

Chi Square ◽

Logistic Analysis ◽

The Relationship

Earlier postpartum cyclicity based on hormonal analysis was related to the subsequent fertility, although it has not been clarified under field conditions. This field study examined the relationship between the detection of corpus luteum (CL) at the first post partum month and subsequent reproductive performance in dairy cows. Holstein dairy cows underwent ultrasonography (Sonoace 600 with 7.5 MHz linear-array transducer; Medison Co. Ltd., Korea) at 30 (±7) days postpartum to determine the existence of CL in ovaries and then divided into 2 groups based on the existence of CL; the CL group (n = 156) or the non-CL group (n = 281). At the same time of ultrasonography, all cows were scored for body condition. Cows received the normal herd reproductive management program including oestrous detection or synchronization, or synchronization of ovulation in the breeding period. Pregnancy was determined per rectum 60 days after artificial insemination by both ultrasonography and palpation. Reproductive performance data were collected for a minimum of 210 days postpartum. Reproduction data between the CL and non-CL groups were evaluated by t-test, chi-square test, or logistic regression using an SAS program (Version 9.1: SAS Institute, Inc., Cary, NC, USA). The proportion of cows with CL in ovaries at 30 (±7) days postpartum was 35.7% of all cows. The number of days to first insemination after calving was more delayed (P < 0.0001) in the non-CL group (100.1 ± 2.7 days) than in the CL group (80.9 ± 2.9 days), while the pregnancy rate to first insemination did not differ (P > 0.05) between the CL group (44.2%) and the non-CL group (45.9%). The CL group had higher pregnancy proportions (PP) within 60 (odds ratio, OR = 2.3; P = 0.0063), 90 (OR = 1.6; P = 0.04), and 120 days (OR = 1.5; P = 0.05) postpartum than the non-CL group; however, the PP within 150 or 210 days postpartum did not differ between the 2 groups (P > 0.05). Besides, logistic analysis revealed that cows with body condition score (BCS) ≥3.00 were more likely to have CL (OR = 1.8; P = 0.015) compared with cows with BCS ≤ 2.75, while primiparous cows were less likely to have CL (OR = 0.6; P = 0.0085) compared with multiparous cows. In addition, cows that underwent ultrasonography later than 30 days postpartum were more likely to have CL (OR = 1.6; P = 0.0192) compared with cows that underwent ultrasonography earlier. In conclusion, the earlier cyclicity based on the detection of CL using ultrasonography at the first postpartum month, which might be in part due to a higher BCS, predicts an enhanced reproductive performance in dairy cows, particularly during the early and early-mid lactations. This work was supported by the research grant of the Chungbuk National University in 2010.

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Reproduction in the mosaic-tailed rat, Melomys cervinipes (Rodentia :Muridae)

Australian Journal of Zoology ◽

10.1071/zo9700171 ◽

1970 ◽

Vol 18 (2) ◽

pp. 171 ◽

Cited By ~ 3

Author(s):

JM Taylor ◽

BE Horner

Keyword(s):

Litter Size ◽

Reproductive Performance ◽

Post Partum ◽

Selective Advantage ◽

Breeding Period ◽

Mode Of Reproduction ◽

Accessory Sex Glands ◽

Modest Contribution ◽

Northern Regions ◽

Autumn And Winter

The mosaic-tailed rat, M. cervinipes, is usually an abundant murid where it occurs in the northern regions of Australia. It is an inhabitant of the forests and their fringe associations and is semi-arboreal. Although the annual reproductive performance is unknown, breeding occurs at least in late spring and summer in more southern areas of its distribution and extends into autumn and winter farther north. Litter size ranges from two to four. The nipple-clinging behaviour of the young appears to be of selective advantage as an escape mechanism. Description of the histology of the gonads and accessory sex glands is given for juveniles, breeding adults, and sexually quiescent adults. M. cervinipes is polyoestrous and a spontaneous ovulator and may experience a post-partum oestrus. Melomys is not known to occur in plague proportions in its native habitat; its mode of reproduction favours a prolonged and modest contribution of young within a breeding period.

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