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The objective of the present study was to use longitudinal data to examine the relationships between blood concentrations of nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHB), and glucose during the transition period in dairy goats. Weekly blood samples were collected from Saanen goats from a commercial herd in Australia [1-7 yr; body weight 70 ± 16.0 kg; body condition score 2.5 ± 0.3; and daily milk yield 2.4 ± 0.73 L/d; all mean ± standard deviation (SD)]. The weekly prevalence of goats above hyperketonemic levels (BHB ≥0.8 mmol/L) was approximately 6 times greater postpartum than antepartum. As well, of the 935 goats sampled antepartum, 50 (5%) had at least 1 hyperketonemic event, and 823 (88%) had at least 1 event of NEFA above the threshold (≥0.3 mmol/L). Of 847 goats tested postpartum, 258 (30%) had at least 1 hyperketonemic event, and 690 goats (81%) had at least 1 event of NEFA above the threshold (≥ 0.7 mmol/L). Substantial variation was found when analyzing the mean days of maximum NEFA and maximum BHB concentrations antepartum (-11 ± 6.6 and -14 ± 7.2 d, respectively, mean ± SD) and postpartum (14 ± 6.6 and 9 ± 6.8 d, respectively, mean ± SD). We observed moderate to strong relationships between NEFA and BHB concentrations (r = 0.66) and between NEFA and glucose concentrations (r = -0.46) throughout the transition period. Our results suggested that 3 to 16 d in milk is the best sampling window for monitoring hyperketonemia in dairy goats, and that results from simultaneous BHB and glucose tests provide an improved indication of the fat mobilization and energy status of the herd when measured close to this timeframe.

The aim of this study was to evaluate temporal variations in circulating levels of selected hormones and metabolites in commercial dairy goats during the transition period. Blood samples from 940 goats were collected weekly, from -3 to 3 wk relative to delivery, to measure the effects of level of milk production, parity number, and litter size on concentrations of glucose, β-hydroxybutyrate (BHB), fatty acids, and plasma urea nitrogen (PUN). A subset of 80 goats [40 low-yielding (LY,1.8 L/d) and 40 high-yielding goats (HY,3.7 L/d)] were selected from the study population to measure the effects of level of milk production on plasma concentration of insulin, prolactin, and growth hormone. Average (±SD) milk yield (from 3 to 30 d in milk), body weight, and body condition score for the study population were 2.4 ± 0.78 L/d, 70 ± 16.0 kg, and 2.5 ± 0.28 units, respectively. Milk yield was moderately correlated with parity number (r = 0.49) but had weak correlation with litter size (r = 0.14). In multiparous but not in primiparous goats, antepartum concentrations of fatty acids and BHB increased with increasing litter size. Concentrations of fatty acids, BHB, and PUN were consistently lower in primiparous goats compared with those in second or greater parity. Postpartum, HY goats had higher ratios of glucose, fatty acids, and BHB to insulin than did LY goats, which might explain the greater mobilization of body tissues and enhanced milk production observed in this group. Collectively, our results indicate that increased milk yield has the most significant influence on the magnitude of body tissue mobilization. Our results also show that goats of higher parity display higher levels of lipid mobilization, and that both pregnancy and lactation are less able to elicit lipomobilization in primiparous compared with multiparous goats.

This experiment aimed to examine endocrine and metabolic responses to glucose, insulin, and adrenocorticotropin (ACTH) infusions in early-lactation dairy goats of different levels of milk production (LMP). Goats were grouped as either high (HY; 4.0 L/d, n = 13) or low milk yield (LY; 2.4 L/d, n = 13). Individual milk yield (L/d) and dry matter intake (DMI; kg/d) were measured daily. Concentration (mM) of glucose, fatty acids, and β-hydroxybutyrate, percent of milk fat and protein, body weight (BW; kg), and body condition score (BCS) were assessed weekly (from 2–6 wk postpartum). An intravenous glucose tolerance test (IVGTT), an insulin tolerance test (ITT), and an ACTH stimulation test were carried out at 43, 44, and 45 ± 0.7 d in milk, respectively. The HY goats had greater milk yield (+67%), energy-corrected milk (ECM; +70%), DMI (+28%), ratio of ECM output to metabolic BW (+67%), and feed efficiency (+25%), but lesser BCS than LY goats (2.4 vs. 2.6). The DMI (% of BW) was moderately correlated with ECM (r = 0.70) and negatively correlated with BCS (r = −0.57). At the time of the IVGTT, HY goats had lesser basal insulin and glucose than LY goats. However, results from IVGTT and ITT indicate that the sensitivity of peripheral tissues to insulin was unaffected by LMP. Compared with LY, HY goats had lesser insulin secretion (−52%) and greater insulin clearance rate (+47%) after glucose infusion. The ITT and ACTH stimulation test results show that both the growth hormone response to insulin and the cortisol response to ACTH were unaffected by LMP. Also, basal plasma concentrations of GH and cortisol were not correlated with glucose and fatty acids concentrations or any performance traits. Collectively, our results suggest that differences between HY and LY goats, concerning milk yield and feed efficiency, were probably more closely related to differences in insulin secretion and clearance than to differences in peripheral tissue responsiveness to the effects of catabolic and anabolic hormones.

The administration of 1200 i.u. pregnant mares' serum gonadotrophin (PMSG) to female goats 2 days before withdrawal of intravaginal progestagen-impregnated sponge led to a biphasic ovulatory response such that up to several ovulation points were present ‘prematurely’ by the time of sponge withdrawal, followed by a ‘superovulatory’ wave of ovulations appearing approximately 2 days after sponge withdrawal. This phenomenon could not be prevented by the administration of increased doses of progestagens, via either two fresh intravaginal sponges, or i.m. progesterone in oil (50 mg daily or 50 mg four times per day). Plasma was sampled from ten goats at 4 h intervals following the administration of PMSG. Eight of the goats had ovulations present within 72 h of the administration of PMSG, but luteinizing hormone (LH) concentrations, determined by radioimmunoassay, were less than 1.5 ng ml−1 throughout this period, indicating that the premature ovulations were not preceded by surges in the release of endogenous LH. When the concentrations of LH in the samples from two of these goats were further determined by bioassay, they were found to have increased from less than 1 ng ml−1 at the time of administration of PMSG to greater than 5 ng ml−1 within 12 h, whereafter they remained elevated for a further 72 h. Thus, we concluded that LH bioactivity inherent within PMSG can directly induce ovulation.

This study investigated the proceptive and receptive behaviour of the ewe in detail, and examined the relationship between these two aspects of female sexual behaviour. In the first experiment, ovariectomized ewes that had received no hormonal treatment (non-oestrus) were observed for 2 min every 4 h for 40 h in a T-maze that contained flock-mate ewes in one arm and rams in the other arm. These non-oestrous ewes spent almost 80% of their time in the T-maze with ewes, indicating that non-oestrous ewes are motivated to be with ewes and/or flock mates rather than rams. In Experiment 2, ovariectomized ewes treated with progesterone and 25 μg of oestradiol benzoate (ODB) were observed in the T-maze for 2 min every 6 h from 18 h before oestrus until 6 h following oestrus. Immediately following the observations in each T-maze test, the ewes were presented to a ram and 4 non-oestrous ewes in an arena (5 × 5 m), and the sexual behaviour of both the ewe and ram was observed for 5 min (Mating Test). This procedure was repeated in Experiment 3, except that 60 μg ODB were used to induce oestrus and observations were carried out every 4 h from 16 h before until 16 h into oestrus. In both Experiments 2 and 3 the ewes spent more time with rams than ewes in the T-maze during oestrus rather than before or following oestrus ( P P P P Overall, these experiments describe the changes that occur in the proceptive behaviour of the ewe relative to oestrus and they indicate that the proceptive behaviour of the ewe consists of both affiliative (tendency to approach and remain with rams) and physical contact (appetitive responses in the Mating Test) responses. The behaviour of the ram reflects the level of proceptive and receptive behaviour of the ewe, emphasizing the importance of the interaction between both sexes. Furthermore, the level of proceptive behaviour of the ewe clearly influences the amount of attention that she receives from the ram and her chances of being mated.

The fertility of naturally mated ewes was compared with the number of spermatozoa deposited, and the number of times they were mated. The number of spermatozoa received was estimated from ejaculates flushed directly from the vagina of naturally mated ewes. In one experiment, maximum fertility was achieved with as few as 140 × 10 6 spermatozoa. The percentage of pregnant ewes was similar in ewes mated once or more than once (68.4% vs. 72.5%). Similar results were obtained in one test of a further experiment but in a second test fertility was higher in ewes that were mated more than once. If this effect was due to the extra spermatozoa received, then ewes required 500 × 10 6 spermatozoa to achieve maximum fertility. Half of the ewes were mated at their first oestrus after treatment with progestagens in the second experiment. The fertility of these ewes was similar to that of the remaining ewes, which were mated at natural oestrus. The mean number of spermatozoa ejaculated by individual rams varied from 140 × 10 6 to 1050 × 10 6 , following depletion of the epididymal reserves of spermatozoa. The rams ejaculated an average of 9.1 × 10 6 spermatozoa per gram of testis per day in the first experiment. The rams mated an average of 10.9 times per day in the first experiment, 6.9 and 6.1 times per day, respectively, for the first and second tests in the second experiment. The number of times that rams mated was highly correlated with the number of ewes with which they mated in the second experiment.

This study investigated the importance of the wool of the ewe in influencing her sexual “attractiveness” to rams and determined if, under field conditions, rams would display mating preferences for woolly over shorn ewes and if rams would be more sexually stimulated by woolly than shorn ewes. In Experiment 1,5 rams were individually presented with 4 oestrous ewes that had 12 months wool (woolly) and a second group of 5 rams was similarly presented to 4 oestrous ewes that had been shorn 5 days before the experiment (shorn). Following this, a separate group of 6 oestrous ewes, containing 3 woolly and 3 shorn ewes, was ranked in order of sexual attractiveness based on the individual selection for the ewes by all 10 rams in a standardized test. Previous exposure of the rams to either woolly or shorn ewes had no effect on ram preferences. In Experiment 2, an order of sexual attractiveness was obtained for 6 oestrous woolly ewes using 10 rams in the standardized test. The 3 most attractive ewes were then shorn and an order of sexual attractiveness was again obtained using the 10 rams. This was replicated with 6 different ewes and 8 different rams. The mean ranks of sexual attractiveness of the ewes before shearing were not significantly correlated with the mean ranks following shearing. There was not a significant order of sexual attractiveness in Replicate 1 following the shearing of the three most attractive ewes, but in Replicate 2 there was a significant order of attractiveness following shearing (P In Experiment 3, each of two groups of 6 rams was observed in a 2-ha field with 9 oestrous woolly ewes and 9 oestrous shorn ewes for 8 h. More woolly ewes (94.4%) than shorn ewes (44.4%) were mated (P In Experiment 4, one of these groups of 6 rams was observed for 4 h when introduced in a 2-ha field to 18 woolly oestrous ewes and then to 18 shorn oestrous ewes. At the same time, the other group of rams was first introduced to shorn ewes and then to woolly ewes. These two tests were repeated 2 weeks later, but the order of testing was reversed. More woolly ewes (81.9%) than shorn ewes (61.7%) were mated (P The results of these experiments demonstrated that some of the components of ewe attractiveness are associated with the wool and that woolly ewes are more sexually attractive than shorn ewes. Under filed conditions, rams prefer to mate woolly ewes and are more sexually stimulated by woolly ewes than shorn ewes.

This experiment investigated whether rams display mating preferences for particular oestrous ewes during field joining, and tested the hypothesis that such preferences are due to differences in the sexual “attractiveness’ of oestrous ewes. In addition, the influence of social interaction between rams on their mating preferences was determined. Each of 10 rams was presented with oestrous ewes in a 0.4-ha mating plot for up to 11 days. No observations were made in a preliminary 5-day period of joining in single-sire mating groups with at least two, and usually six, oestrous ewes per ram per day. For the next 6 days the rams were joined singly and then in groups of two and three at the rate of six oestrous ewes (that were 0–4 h into oestrus) and 30 non-oestrous ewes per ram. The rams were allocated to groups of two and three on the basis of their dominance status, which had been established earlier from competition by the rams for a bucket of feed. The behaviour of all animals was observed continuously until one of the ewes was no longer in oestrus. All rams displayed clear mating preferences, and this resulted in an uneven distribution of mating among the available oestrous ewes, with 24.8% (58234) of the ewes not being mounted. Rams were actively discriminating between ewes, since they investigated 87% (8092) of the ewes that were not mated and were able to locate the oestrous ewes in a group that also contained non-oestrous ewes. Also, the correlation between the number of ejaculations received by ewes and the number of times they “solicited” attention from the rams was only 0.28. This suggests that the “soliciting” behaviour of the ewes had less influence on whether or not they were mated than did the rams mating preferences. The Spearman's rank correlations between the ejaculations and the observable components of ram behaviour received by the ewes were highly significant (P

Ewes that were untreated, fed lupins or fed lupins and immunized against androstenedione were artificially inseminated. The percentage of ewes pregnant at 36-45 days after insemination (fertility) was 8% higher in ewes that had more than one ovulation than in those that had only one ovulation. Maximum fertility was achieved with 50 x 10(6) spermatozoa and this did not vary with the number of ovulations that ewes had. Among the pregnant, twin-ovulating ewes, embryo survival increased as the number of spermatozoa inseminated increased from 25 x 10(6) to 400 x 10(6). Immunization of ewes against androstenedione increased ovulation rate but reduced fertility, and reduced embryo survival among twin-ovulation ewes.