The energy cost of reproduction in sheep

Brockway, J. M.; McDonald, J. David; Pullar, J. D.

doi:10.1113/jphysiol.1963.sp007152

Cited by 25 publications

(6 citation statements)

References 7 publications

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“…Part of this increment would probably be accounted for by an increase in vaporization caused by the extra heat produced in pregnancy. Brockway, McDonald & Pullar (1963) measured the heat production of non-pregnant ewes and of ewes throughout the course of pregnancy, both fed at the same level. The extra heat produced during pregnancy was 400 Mcal and, although they did not investigate the partition of the loss of this heat, some of it would be lost by an increase in vaporization.…”

Section: Discussionmentioning

confidence: 99%

The water intake of ewes

Forbes

1968

Br J Nutr

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1. Two experiments were carried out with non-pregnant ewes in which individual drymatter intake (DMI) and total water intake (TWI) were measured. TWI was closely correlated with DMI; TWI/unit DMI was higher for silage than for cubed dried grass and with both foods water intakes were higher than with long hay.2. Twelve ewes were fed on silage and twelve on hay from the 9th to the 19th week of pregnancy. TWI/unit DMI of each feed doubled during this period. Another twenty-four ewes were fed on silage from the 14th to the 20th week of pregnancy. TWI/unit DMI was positively related to litter size.3. Fifteen ewes were fed on hay from the 4th week of pregnancy until the 7th week of lactation. Milk yield was estimated weekly. Six non-pregnant ewes were controls. TWI/unit DMI for the seven twin-bearing and the nine single-bearing ewes in the last 4 and 3 weeks of pregnancy respectively was significantly higher than that of the six non-pregnant ewes. In the control group TWI/unit DMI was closely related to environmental temperature. In the first 4 weeks of lactation TWI/unit DMI was greater than the sum of TWI/unit DMI of the non-pregnant ewes plus the water in the milk.4. The results supplement those used by the Agricultural Research Council (1965) to assess the water requirements of sheep.

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Section: Discussionmentioning

confidence: 99%

The water intake of ewes

Forbes

1968

Br J Nutr

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“…This finding is in general agreement with the conclusions of Roberts (1964). The duration of the temperature drop overlaps the period of increased heat loss described by Brockway et al (1963).…”

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confidence: 84%

“…Few investigators have studied the temperature of the ewe around the time of parturition although McKenzie & Bogart (1934) give the average body temperature of ewes for the 2 days before and the 7 days after lambing as 39-4°C ; Hafez, Badreldin & Sharafeldin (1956) found that pregnancy has no effect upon the body temperatures of Egyptian fat-tailed sheep ; and Roberts (1964) briefly reported (without quoting results obtained) that the deep vaginal temperature has little practical value in predicting the time of onset of parturition. One factor affecting body temperature is rate of heat loss and it is of interest that Brockway, McDonald & Pullar (1963) reported an increase in heat loss to the environment for sheep during the last 24 hr of pregnancy.…”

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confidence: 99%

The Fall in Rectal Temperature Seen Before Parturition in Sheep

Ewbank¹

1969

Reproduction

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Summary. In the pregnant ewe, there is a general decline in rectal temperature of the order of 0\ m=. \ 7\ s=deg\ C over the 54 hr before parturition. Individual variation, however, makes this temperature drop unreliable for the prediction of the possible time of onset of lambing.Several of the domesticated animals show a slight rise in body temperature in late pregnancy and a temperature decline in the period just before parturition (Weisz, 1943). In cattle (Ewbank, 1963)

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“…For sea otters, this decline occurs over a 3 month period (Esslinger et al, 2014) and may be associated with metabolic changes (Table 1). A decline in RMR during gestation contrasts with patterns observed in most terrestrial mammals (Brockway et al, 1963;Fleming et al, 1981;Garton et al, 1994;Poppitt et al, 1994;Stephenson and Racey, 1993a,b;Thompson and Nicoll, 1986), but agrees with changes observed in phocids (Hedd et al, 1997;Renouf and Gales, 1994;Sparling et al, 2006). In terms of lactation energetics, sea otters conform more to patterns observed in terrestrial rather than marine mammals, which appear to have negligible milk production costs (Costa and Trillmich, 1988;Costa et al, 1986;Williams et al, 2007).…”

Section: Resultsmentioning

confidence: 41%

“…The first study to estimate pup rearing costs in sea otters suggested that female energy demands reach twice prepartum levels by the time a pup nears weaning (Thometz et al, 2014); however, this study only examined the metabolic needs of pups and could not account for the energetic cost of milk production. In general, terrestrial mammals exhibit increased resting metabolic rate (RMR) during lactation, although the extent and duration of this increase are highly variable among species (Brockway et al, 1963;Fleming et al, 1981;Garton et al, 1994;Hammond and Diamond, 1992;Harder et al, 1996;Król et al, 2003;Poppitt et al, 1994;Prentice et al, 1989;Spaaij et al, 1994;Speakman and Mcqueenie, 1996;Stephenson and Racey, 1993a,b;Thompson and Nicoll, 1986). In contrast, the cost of milk production in marine mammals appears minimal in the species studied to date (Antarctic and Galapagos fur seals: Costa and Trillmich, 1988; Northern elephant seals: Costa et al, 1986; California sea lions: Williams et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

The high cost of reproduction in sea otters necessitates unique physiological adaptations

Thometz

Kendall

Richter

et al. 2016

Journal of Experimental Biology

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Superimposed on inherently high basal metabolic demands, the additional energetic requirements of reproduction can push female sea otters beyond physiological limits. Indeed, the resulting energy imbalance contributes to disproportionately high rates of mortality at the end of lactation in this species. To examine and quantify metabolic changes associated with reproduction, we measured the resting metabolic rate (RMR) of a female sea otter across gestation, lactation and non-reproductive periods. Concurrently, measurements were made on a non-breeding control female. Our results suggest that RMR declines during gestation. Conversely, RMR increases during lactation, reaches a peak at 3-4 months postpartum, and remains elevated until weaning. Combining these direct measurements with published data, we found the cost of pup rearing to be significantly higher than previously estimated. High baseline energy demands and limited energy reserves, combined with significant lactation and pup rearing costs, appear to necessitate metabolic and thermal lability during key reproductive stages.

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The energy cost of reproduction in sheep

Cited by 25 publications

References 7 publications

The water intake of ewes

The water intake of ewes

The Fall in Rectal Temperature Seen Before Parturition in Sheep

The high cost of reproduction in sea otters necessitates unique physiological adaptations

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