The relationship of lamb growth from birth to weaning and the milk production of their primiparous crossbred dams

Abstract

The growth rate of 667 single cross lambs from birth to 4 weeks (Period 1) and 4 weeks to weaning at 12 weeks (Period 2) was measured, along with the milk production of their 520 primiparous crossbred ewe dams over 3 years. The lambs were the progeny of Poll Dorset rams and first cross ewes lambing for the first time at 12 and 19 months of age. The first cross ewes were the progeny of Merino ewes mated to 30 individual sires from several maternal sire breeds, including Border Leicester, East Friesian, Finnsheep and Coopworth. Milk production of the ewes was measured at ~3, 4 and 12 weeks of lactation using a 4-h milk test. The effect of ewe milk production on lamb growth rate in Period 1 included a significant interaction with lamb birth and rearing type (P < 0.001). These regressions were 52 ± 18 g/day per kg/day for single born and reared, 24 ± 17 g/day per kg/day for multiple born and single reared and 18 ± 17 g/day per kg/day multiple born and reared lambs. The regression of ewe milk production in Period 2 on lamb growth rate in Period 2 was also significant (P < 0.001), although milk production in Period 1 accounted for more variation in lamb growth. There were significant interactions of ewe weight gain (from mid pregnancy to lamb weaning) with season in Period 1 (P < 0.01) and year in Period 2 (P < 0.001). There was also a significant interaction (P < 0.001) of year with ewe mid-pregnancy weight for lamb growth in Period 2. Lamb birthweight had a significant effect on lamb growth rate in Period 2 (regression coefficient 6.68 ± 2.57 g/day.kg, P < 0.01).

Altering ewe nutrition in late gestation: II. The impact on fetal development and offspring performance1

“…The greater estimated milk production observed from ewes offered the 120% ME treatment (McGovern et al, 2015) is reflected in increased growth rates from their offspring during the first 3 wk of life. Similar to observations made in the current study, greater milk yields in early lactation have been previously shown to give lambs a weight advantage that remains present up until weaning (Morgan et al, 2007). In contrast, lambs born to ewes that received the 80% ME treatment were disadvantaged by reduced milk yields in early lactation but had the potential to achieve growth rates equivalent to their counterparts from wk 4 until weaning.…”

“…However, imposing a more severe restriction for a longer interval before or during gestation may have more profound effects on maternal behavior, as seen in studies performed by Dwyer et al (2003) and Hernandez et al (2010). The ability of the ewe to produce milk is a key driver of early lamb growth and, ultimately, survival (Morgan et al, 2007;Tygesen et al, 2008). The strong correlation identified between lamb growth rate and ewe milk production (Snowder and Glimp, 1991) allowed for the estimation of milk yield in the present study, using an equation as determined by Robinson et al (1969).…”

“…Rearing rank significantly affects lamb growth rate (Morgan et al, 2007), primarily due to the volume of milk available to the lamb (Kenyon et al, 2011a). In a study performed by Galvani et al (2014), lambs that had a 20% increase in milk intake had a 33% increase in growth a-d Within a row, means without a common superscript differ significantly (P < 0.05).…”

Effect of concentrate supplement and sward height on twin-bearing ewe body condition and the performance of their offspring

“…The differences in ewe liveweight between treatment groups, and the lack of differences in lamb birthweight, suggests that nutrients may have been partitioned towards the ewes for mammary development or to prevent body condition loss rather than fetal growth. This may have a positive effect on milk production in early lactation and on lamb growth from birth to weaning (Morgan et al 2007). Supplementation has been shown to have a positive effect on colostrum let down (Banchero et al 2007), although in this study, where lamb plasma GGT concentrations were used as an indirect measure of colostrum intake, no differences were found.…”

Altering ewe nutrition in late gestation: I. The impact on pre- and postpartum ewe performance1

“…Profitability in the livestock industry is driven by the efficiency of production characteristics such as the growth and development of offspring postpartum (Redmer et al, 2004). The plane of nutrition available to the ewe during gestation has been shown to positively influence both udder development and subsequent lactation performance (Blair et al, 2010), and the ability of the dam to produce milk for her offspring is a key driver of neonatal growth and development (Morgan et al, 2007). Optimal maternal nutrition and subsequent fetal growth, as precursors of efficiency, are therefore critical in determining the profitability of meat and lamb production enterprises (Redmer et al, 2004).…”