Once-daily Suckling Research Articles

Metabolic and luteal function in winter‐calving Spanish beef cows as affected by calf management and breed

This experiment aimed at evaluating the effect of calf management and breed on the metabolic and luteal function of post-partum beef cows fed at maintenance. Fifty multiparous cows, 22 Parda de Montaña (PA) and 28 Pirenaica (PI), were assigned to either suckling once-daily for 30 min (RESTR) or ad libitum (ADLIB) from the day after calving. Blood samples were collected to analyse metabolites [non-esterified fatty acids (NEFA), beta-hydroxybutyrate, total protein and urea)], insulin-like growth factor-I (IGF-I) and progesterone (P4) at different intervals. Cows from RESTR maintained their live-weight (LW) over the first 3 months post-partum, whereas ADLIB cows lost nearly 4% LW. Both genotypes showed similar LW gains during this period (p > 0.10). Calf daily gains were lower in RESTR than in ADLIB treatment (p < 0.05), but similar across breeds (p > 0.10). Milk and lactose production were lower in RESTR cows than in ADLIB (p < 0.05). Milk and protein yield were greater in PA than in PI breed (p < 0.05). Serum NEFA, total protein and urea were higher in PI cows suckling ADLIB than in the rest (p < 0.05). Cows from PI breed had greater NEFA values than PA ones on the first week post-partum (p < 0.001). Circulating IGF-I was not affected by suckling frequency, breed nor their interaction (p > 0.10). Suckling frequency, but not breed, affected the interval from calving to first ovulation (p < 0.001), being shorter in RESTR than in ADLIB cows. In conclusion, the ad libitum suckling practice improved cow milk yield and offspring gain compared to once-daily suckling for 30 min from the day after calving, at the expense of impairing the onset of cyclicity. The effect of calf management was confounded with breed on the studied blood biochemical constituents, but any of these metabolites influenced the role of endocrine IGF-I in these genotypes.

Improve Reproductive Performance in Your Cow Herd Using Calf Removal

AN166, a 5-page fact sheet by Gary R. Hansen, discusses three methods of calf-removal and when to use each: short-term calf removal, once-daily suckling, and early weaning. Includes references and tables. Published by the UF Department of Animal Sciences, September 2006.

Comparative effects of early weaning or once-daily suckling on occurrence of postpartum estrus in primiparous beef cows

We concurrently evaluated early weaning and once-daily suckling as options for shortening postpartum interval to estrus in primiparous cows calving in good body condition. Over 2 consecutive years, a total of 77 primiparous cows were assigned to 1 of 3 treatments: control (ad libitum suckling); once-daily suckling (for 30 d prior to start of breeding); or early weaning (calves weaned 30 d prior to start of breeding). All cows had a body condition score (BCS) of ≥ 5 at parturition and were maintained in good condition throughout the breeding season. Cows were observed for estrus twice daily and blood samples for subsequent measurement of progesterone were collected at 48-h intervals. For data analysis, cows were divided into early- (≥85 d post partum) and late-calving (< 85 d post partum) groups at the onset of the breeding season. All calves were weighed at birth, at the onset of treatment, at weekly intervals until the start of the breeding season, and within 45 d of 205 d of age. Early weaning or once-daily suckling shortened the postpartum interval to first estrus of late-calving primiparous cows by 17 (P < 0.01) and 12 d (P < 0.08), respectively, compared with control group cows. However, among early-calving cows, neither early weaning nor once-daily suckling influenced the postpartum interval. Postpartum intervals of once-daily suckled cows and early-weaned cows were similar (P > 0.10).

Effect of calf isolation on follicular wave dynamics, gonadotropin and metabolic hormone changes, and interval to first ovulation in beef cows fed either of two energy levels postpartum.

The effects of postpartum energy intake, restricted suckling, and cow-calf isolation on concentrations of LH, FSH, growth hormone, and insulin-like growth factor-I (IGF-I) and on postpartum anestrous interval were determined by randomly allocating beef cows with a mean body condition score of 2.3 +/- 0.1 to receive either 80 MJ metabolizable energy (low-energy diet [L]; n = 51) or 120 MJ metabolizable energy (high-energy diet [H]; n = 52) per cow per day from calving. At 30 days postpartum, cows within diet were randomized to 1) have continued full access to their calves from birth to weaning (ad libitum suckling: ADLIB), 2) be suckled once-daily with their calves penned adjacent (restricted suckling, adjacent: RESADJ), 3) be isolated from all calves except for a once-daily suckling period (restricted suckling, isolated: RESISO). The mean postpartum interval was similar (p > 0.10) for L and H cows (62 and 63 days, respectively). RESADJ cows had a shorter (p < 0.05) postpartum interval than ADLIB cows, and RESISO cows had a shorter interval (p < 0.05) than RESADJ cows, with all effects independent (p > 0.10) of diet. FSH secretion pattern was not affected by diet, suckling treatment, sequential follicle wave number, or follicle wave retrospectively realigned to emergence of first ovulatory wave. Within 5 days of suckling restriction and calf isolation, the number of LH pulses increased from 0.18 to 0.48 pulses per hour (p < 0.05). Both mean LH and the mean number of LH pulses increased linearly (p < 0.01) during the six follicle waves up to the first ovulatory wave. From 80 days before, until the time of, first ovulation, growth hormone decreased (p < 0.05) while IGF-I increased (p < 0.05), irrespective of treatment. The results indicate that the "suckling effect" in beef cows is the major factor affecting the duration of the postpartum interval and suggests that the maternal bond is more important than suckling in regulating LH pulse frequency, the key endocrine factor determining whether or not a dominant follicles ovulates. Removal of the suckling effect resulted in a rapid increase in LH pulse frequency, which was not dependent on level of postpartum nutrition, at least within the nutritional limits of this study. Mean concentrations of FSH, unlike LH, did not vary with follicle wave number, suggesting that lack of FSH is not a major factor delaying the resumption of ovulation in postpartum beef cows.

Effect of once-daily suckling on postpartum reproduction in zebu-cross cows in the tropics

A trial was conducted in the tropical area of Mexico. Eighty-nine multiparous zebu-cross lactating cows were assigned by calving date and body condition to either of the following treatments: (1) no suckling manipulation (control; n = 44); (2) once-daily suckling ( n = 45). The suckling manipulation period began at 30 days post calving and lasted 30 days; thereafter, calves continued to nurse their dams until weaning (8 months old) without any supplemental creep feed. Both groups were maintained on pasture for a 90 day breeding period (May–July) with semen-tested bulls. The data were analyzed using a linear model procedure. The average calving-conception interval was not affected by treatment (83 ± 8 vs. 78 ± 8 days for control and treated groups respectively); however, the pregnancy rate at 60 days and 90 days of the breeding period was significantly greater ( P < 0.05) for the treated group than for the control group (81% and 90% vs. 59% and 72%, respectively). The average daily gain for calves and also the weaning weights were not affected by treatment ( P > 0.05). It was concluded that once-daily suckling did increase the pregnancy rates of zebu-cross cows without depressing the growth performance of the calf.

Effects of postpartum nutrition and once-daily suckling on reproductive efficiency and preweaning calf performance in fall-calving Brahman (Bos indicus) cows

Brahman cows were used to evaluate the effects of postpartum nutrition and suckling on reproductive and calf performance. Cows received high or low TDN and once-daily or unrestricted suckling. High TDN (H; 111% of NRC recommendation) cows received a 75% corn: 25% soybean meal diet. Low TDN (L; 93% of NRC recommendation) cows received no concentrates. Once-daily suckled (restricted, R) cows nursed calves for 30 min/d starting at d 21 after calving. In the unrestricted (U) suckling groups, calves had continuous access to cows. By 2 wk of suckling restriction, more (P < .01) R than U cows had progesterone concentrations of > or = .7 ng/mL (55 vs 0%) and more (P < .05) HR than LR cows had progesterone concentrations > or = .7 ng/mL (70 vs 40%). All groups had increases in progesterone and 13,14-dihydro-15-keto-prostaglandin F2 alpha before estrus. The interval to first estrus was shorter (P < .01) for R than for U cows (42 vs 65 d). By d 42 postpartum, more (P < .01) R than U cows exhibited estrus (67 vs 0%), and more (P < .05) HR than LR cows exhibited estrus (89 vs 44%). Calving interval was shorter (P < .01) for R than for U cows (361 vs 395 d). Initial ADG were lower (P < .01) for R than for U calves (.02 vs .69 kg), but weaning weights were similar. Once-daily suckling permitted ovarian activity, hastened return to estrus, and reduced calving interval without reducing weaning weights. Increased postpartum energy intake enhanced the response to restricted suckling.

Effect of suckling manipulation on postpartum reproduction in primiparous Brahman-cross cows

The effect of suckling manipulation on postpartum reproductive performance was investigated in 106 primiparous Brahman-cross cows. Suckling manipulation treatments were 1) suckling ad libitum (SAL, n = 52) and 2) once-daily suckling (ODS, n = 54) beginning at 30 d after parturition. By 60 d after parturition, 57% of the ODS and 29% of the SAL groups, respectively (P<0.005), exhibited estrus. By 90 d after parturition, 74 and 63% of the cows exhibited estrus in the ODS and SAL groups, respectively. The pregnancy rates by 60 d were 31 and 12% in the ODS and SAL groups, respectively (P<0.005). By 90 d, 61 and 44% of the ODS and SAL groups had conceived (P<0.10). Least squares means for the postpartum interval to estrus were 57 ± 4 and 82 ± 4 d for the ODS and SAL groups, respectively (P<0.05). The least square means for the postpartum interval to conception were 71 ± 4 and 82 ± 4 d for the ODS and SAL groups, respectively (P<0.05). In summary, once-daily suckling did increase the percentage of cows returning to estrus and pregnant by 90 days. Therefore, once-daily suckling is a successful management regimen for reducing the length of the postpartum interval to estrus and to conception in primiparous Brahman-cross cows.

Effect of alfaprostol, lasalocid, and once-daily suckling on postpartum interval in Brahman and Brahman crossbred cattle

Brahman cows (n = 49) and primiparous heifers (n = 11), Brahman × Hereford primiparous F1 heifers (n = 86) and Simmental × Brahman primiparous F1 heifers (n = 13) were randomly allotted by breed, age and date of calving to one of eight treatment groups: 1) control; 2) once-daily suckling; 3) lasalocid (200 mg/hd/d); 4) alfaprostol (5 mg intermuscular injections on Days 21 and 32 post partum); 5) lasalocid + once-daily suckling; 6) alfaprostol + once daily suckling; 7) alfaprostol + lasalocid; 8) alfaprostol + lasalocid + once daily suckling. All animals received 2.3 kg/hd/d of a concentrate (6 corn : 1 cottonseed meal) and lasalocid was mixed and fed in the concentrate. Body weights and condition scores were taken on Day 1 post partum and every 28 d thereafter. All animals were maintained with sterile marker bulls with Brahman and Simmental × Brahman cattle artificially inseminated at first estrus. Blood samples were collected at weekly intervals starting on Day 21 post partum until estrus and at nine to twelve days post estrus when the ovaries were palpated for corpora lutea. After the first postpartum estrus with a corpora lutea, cows were placed with fertile bulls. Mean serum progesterone concentrations were below 0.5 ng/ml prior to treatment. Calf weight gains to 90 d were not affected by age (P > 0.10) but were lower in the once-daily suckling group (P < 0.05). Treatment did not affect cow weight or condition score (P > 0.10). Cows had a shorter postpartum interval (P < 0.0001) than heifers. Once-daily suckling shortened postpartum interval (P < 0.0001) and positively influenced the cumulative frequency of return to estrus by 40 d post partum (P < 0.02). Alfaprostol did not affect postpartum interval (P > 0.10) but did increase the cumulative frequency of return to estrus by 90 d post partum (P < 0.03). Lasalocid did not affect postpartum interval or cumulative frequency of return to estrus (P > 0.10). Both once-daily suckling and alfaprostol were effective in increasing the numbers of animals inseminated by 90 d post partum. The once-daily suckling + alfaprostol treatment resulted in the shortest postpartum interval.

Effect of forty-eight-hour calf removal, once- or twice-daily suckling and Norgestomet on beef cow and calf performance

Trials were conducted in 1980 and 1981 to evaluate the effects of once-daily suckling, twice-daily suckling, 48-h calf removal, and Norgestomet on performance of spring-calving cows and their calves. Eighty-three and 73 Polled Hereford and 29 and 42 Simmental-cross cows were utilized in 1980 and 1981, respectively. Cows were allotted by age, breed, calving date and winter nutrition treatment to one of four groups: 1) once-daily suckle for 24 d starting 11 d before the beginning of the breeding season, 2) twice-daily suckle (same time frame as 1), 3) 48-h calf removal ending immediately before the breeding season, 4) calves remained with cows (controls). One-half.of each group was implanted with Norgestomet b b Norgestomet (17 acetoxy-11 methyl-19 nor-preg-4-ene-3, 20-dione), a synthetic progestogen, was provided by G. D. Searle & Co., Chicago, IL. from 11 until 2 d before the start of the breeding season. Once- and twice-daily suckling increased (P<0.05) the percentage of noncycling cows showing estrus the first 3 wk after the start of treatment. Pregnancy rates for the breeding season were higher (P<0.1) in the once-daily suckle and 48-h calf removal groups for cows that had not exhibited estrus before the beginning of treatment. Norgestomet increased (P<0.05) the percentage of cows showing estrus within 3 wk after the start of treatment within the 48-h calf-removal and control groups. Milk production was not affected (P>0.1) by suckling treatment. Calf weight gains during suckling treatment were greater (P<0.05) in control and twice-daily suckled calves than in 48-h calf removal or once-daily suckled calves. Suckling treatment did not affect (P>0.1) adjusted weaning weights of calves or frequency and duration of suckling recorded 2 wk after the end of suckling treatment.

Reproductive response to suckling manipulation in Spanish goats

One hundred and fifty-six Spanish does were used to evaluate the effect of suckling manipulation on postpartum breeding. Does were divided into four herds dependent upon their kidding dates (range from October to January) and location. All kids were nursed ad libitum for approximately 30 days following birth. Groups were then subdivided, and does with kids were randomly allotted to one of the following treatment groups: 1) continuous suckling (CS), 2) once-daily suckling (ODS) or 3) early weaning (EW). Nonlactating does (NL) which lost a kid or aborted were also evaluated for rebreeding performance. At least one fertile male equipped with a marking harness was placed with each treatment group for estrus detection. After 30 days, ODS kids were returned to their dams. The proportion of does exhibiting estrus within 60 days postpartum was greater for ODS and EW does compared to CS does (P<0.05 and P<0.001, respectively). Postpartum interval to first estrus was shorter (P<0.05) for ODS does than for CS does (41.7 and 48.0 days, respectively). The percentage of does conceiving within 60 days postpartum was 25.0, 44.7, 74.4 and 70.7% for CS, ODS, EW and NL does, respectively. The interval from parturition to conception was shorter (P<0.05) for ODS does (43.6 days) than for CS does (50.4 days). Overall kid production was 1.87 kids/doe/year. These results indicate that reducing the suckling stimulus in Spanish does during the breeding season may result in an earlier return to estrus with a greater percentage of does rebreeding within 60 days postpartum.

Release of oxytocin and prolactin by suckling in rabbits throughout lactation.

Plasma oxytocin and PRL were measured in serial samples of blood collected from lactating rabbits nursing five to seven (mean, six) young on a once-daily suckling regimen. Each suckling episode lasted 4.0 +/- 1.1 (+/- SD) min on the average. Samples were obtained by means of an indwelling cardiac catheter before and 1, 3, 5, 10, 20, 30, and 60 min after suckling began. Measurements were performed at several stages of early, mid-, and late lactation. Oxytocin levels rose to peak values during suckling and declined rapidly after suckling stopped. PRL levels, on the other hand, did not reach peak values until 1-5 min after suckling had stopped, at which time plasma PRL concentrations plateaued and, in early and midlactation, were sustained at peak levels for 2-3 h; in late lactation, PRL secretion was not sustained after suckling had ceased. Peak PRL levels were relatively constant throughout most of lactation, with no significant differences between groups until late in lactation, when peak levels fell rather abruptly from a mean of 74 +/- 33.5 to 10.5 +/- 13.3 (+/- SD) ng/ml around day 25 in spite of a constant number of young and constant suckling frequency. Suckling failed to elicit any PRL release on day 30, but the administration of fluphenazine, a dopamine antagonist, did cause a rise in plasma PRL. Oxytocin release increased with advancing lactation, rising, on the average, 40 pg/ml on day 2 and to 250 and 490 pg/ml in mid- and late lactation, respectively. Dopaminergic agonist and antagonist drugs given to the doe before the nursing episode did not influence oxytocin release in response to suckling. Without a rise in plasma oxytocin, the young obtained no milk, but above a threshold level, there was no significant correlation between peak oxytocin levels and milk yield. When suckling failed to induce PRL secretion, milk secretion ceased rapidly in spite of copious oxytocin secretion. The failure of suckling to induce PRL release in late lactation, therefore, appears to be an important factor in the cessation of lactation.

Effects of once-daily suckling and twice-daily suckling on postpartum reproductive performance of beef cows and on growth and ingestive behavior of their calves.

Effects of once-daily suckling and twice-daily suckling on postpartum reproductive performance of beef cows and on growth and ingestive behavior of their calves.

Effect of Once-Daily Suckling on Postpartum Interval and Cow-Calf Performance of First-Calf Brahman × Hereford Heifers

Effect of Once-Daily Suckling on Postpartum Interval and Cow-Calf Performance of First-Calf Brahman × Hereford Heifers

Milk ejection reflex and maintenance of lactation in the rabbit.

Lactating rabbits were deeply anesthetized once daily with barbiturate, suckled by their young only during the period of anesthesia, and injected with oxytocin to eject the otherwise unobtainable milk. The oxytocin-delivered daily milk yields of these animals, when suckled under anesthesia, were in the same range as those recorded prior to the regimen of anesthesia during a control period of once-daily suckling without anesthesia or exogenous oxytocin. Reflex discharge of milk in response to the suckling stimulus does not, therefore, appear to be essential for the secretion or release of those adenohypophysial hormones concerned with the maintenance of milk secretion in the rabbit.