Elsevier

Small Ruminant Research

Volume 161, April 2018, Pages 13-23
Small Ruminant Research

The effects of nutrition and parity on the development and productivity of Angora goats: 3. Effects of six combinations of mid pregnancy and postnatal nutrition on udder development, lactation, milk composition and net energy of milk production

https://doi.org/10.1016/j.smallrumres.2018.02.005Get rights and content

Highlights

  • Both postnatal nutrition and parity had large effects on lactation.

  • Fat corrected milk production for the first 6 weeks of lactation can exceed 2.8 kg/d.

  • Nutrition affected net energy requirements per kg milk production.

  • Udder volume of Angora does was positively correlated with milk production.

  • Milk production and daily energy needs are underestimated in existing literature.

Abstract

Recommendations for the nutrient management of lactating Angora goats are mostly based on theoretical calculations as little empirical data is available. This report investigates the combined effects of 3 levels of mid pregnancy nutrition (MPN) × 2 levels of postnatal nutrition during lactation (PNN) providing 6 nutrition patterns, with both single and twin bearing does, on milk production and composition and energy requirements for milk production. Following artificial insemination and pregnancy scanning, does were fed pelleted rations in individual pens in an outdoor feedlot from day 47 of pregnancy until 13 weeks postpartum. MPN treatments commenced from day 47 as follows: Control (C), fed to lose live weight (−67 g/d); Maintenance (M), does fed to maintain live weight; Supplemented (S), does fed to gain live weight at 102 g/d. From days 105 of pregnancy until 4 days postpartum the feeding level was ad libitum for all treatments. From 4 days postpartum PNN treatments were: ad libitum (AL) to allow maximum ME intake resulting in live weight gain throughout lactation; Restricted (R) to 70% of AL, resulting in live weight loss until week 10 of lactation. MPN had no effects on milk production. Milk production was affected by PNN and parity at days 21 and 42 of lactation but not at day 90. R fed does secreted 21% less milk at day 21 of lactation (1.75 vs. 1.38 kg) and 29% less at day 42 of lactation (1.74 vs. 1.24 kg) compared with AL fed does. Milk production corrected to 4% fat exceeded 2.8 kg/d until day 42 of lactation in AL fed does. Both MPN and PNN affected the concentration of milk solids. MPN had no effect on secretion of milk solids. PNN affected total secretion of milk fat, protein, lactose and total solids at days 21 and 42, with AL fed does producing more than R fed does. Both MPN and PNN had separate independent effects on NEl. For MPN, S fed does had milk with higher NEl than that of M and C fed does (C, 5.256; M, 5.320; S, 5.683 MJ/kg; P < 0.05). For PNN, R fed does had milk with higher NEl than that of AL fed does (R, 5.614; AL, 5.226 MJ/kg; P = 0.005). Total NE secreted in milk was affected by stage of lactation (P < 0.001) and separate effects of PNN (P= 0.001) and parity (P= 0.014). There were significant correlations between udder dimensions and milk production and composition. Higher ME intake was associated with higher milk production (days 21 and 42), and higher body condition score was associated with higher milk production. At day 42, does rearing male kids had greater milk production compared those rearing female kids. Does with udders of greater volume produced more milk. Total milk production during lactation was highest for AL fed twin rearing does at 201 kg and lowest for R fed single rearing does at 85 kg. Both milk production and milk fat composition were substantially greater than earlier reports for Angora does. The results indicate that previously suggested daily ME requirements of lactating Angora does and their potential daily milk yield need substantial upwards revision.

Introduction

Angora goats in Turkey have been traditionally kept by nomadic pastoralists for their milk, meat, mohair, leather and other social needs. From a livelihood perspective, cost benefit studies in Turkey indicate that milk production still represents 39% of the value of production from Angora goat enterprises (Çelik and Bayramoğlu, 2010). Daskiran et al. (2010) surveyed 100 Angora farms in 5 districts of the Ankara province. Based on interviews they reported daily Angora goat milk production varied significantly between districts with an average of 1.83 kg/day (range 1.43–2.19 kg/day).

Little empirical research has been conducted on the nutrient requirements for breeding and lactating Angora goats. Together, Shelton (1993), who summarised his long experience researching Angora goats in Texas, and van der Westhuysen et al. (1988), who provide the industry wisdom for the South African mohair industry, provide evidence from only one study on the lactation performance of Angora does. Thus, recommendations for the nutrient management of lactating Angora goats are mostly based on theoretical calculations, and more generally NRC (1981) and Luo et al. (2004). In their detailed analysis of nutrient requirements for goats, Luo et al. (2004) specifically excluded lactating Angora does from their modelling given the dearth of reports. Thus, what constitutes normal lactation for Angora goats and the effects of nutritional manipulation during pregnancy and lactation have not been adequately investigated. In providing advice on the nutritional requirements of breeding Angora goats to Texan breeders, and in the absence of any objective data, Huston et al. (1971) assumed milk production of 0.68 kg/d with a composition of 4.5% fat and 3.5% protein. This milk yield is much lower than those typically obtained with specialist dairy goat breeds (Gipson and Grossman, 1989), although the composition of dairy goat breeds is typically about 3.8% fat (Jenness, 1980).

The lactation curve of dairy goat breeds typically extend to about 300 days. Daily milk yield is reported to increase from kidding time to peak at 4–6 weeks postpartum before a long and steady decline. Both peak and total milk production in dairy goats differs between breeds and individual goats, is greater for twin parity compared with single parity rearing does and can be affected by nutritional manipulation and seasonal conditions (Morand-Fehr et al., 1991, Morand-Fehr et al., 2007). There are some well-known influences of farming and feeding practices on the lactation performance of dairy goats. It is clear from studies with dairy goats and breeding sheep and cattle that energy intake is the prime factor affecting lactation performance and offspring productivity (SCA, 1990). Daily milk production and peak production depend upon the energy density of the diet during the last trimester of gestation (Sahlu et al., 1995) and the optimal energy density varies during lactation (Morand-Fehr and Sauvant, 1978a, Morand-Fehr and Sauvant, 1978b). Morand-Fehr et al. (1991) described the interdependence of 12 factors which influence milk composition including level of production, nutrition, milking practices, season, photoperiod, climate, pathological issues, genetics and stage of lactation. Generally, with dairy goats, there is an inverse correlation between daily milk production and the concentration of milk solids.

During pregnancy, the requirements for the growth of tissues varies as the pregnancy progresses. Placental growth is completed by 100 days (Redmer et al., 2004). Mammary gland development occurs in the last trimester of pregnancy, particularly the last 4 weeks (Rattray et al., 1974). Jenness (1980) recommended that udder measurements be used in breeding programs for dairy goats given their association with milk yield. In Toggenburg dairy goats, udder characteristics are significantly correlated with milk yield and were highly heritable (Wang, 1989). Anderson and Wahab (1990) described the changes in udder growth and development during pregnancy and lactation in breeds of dairy goat. Stroma, which are the supportive structures in the mammary gland represent 60% of udder weight in early pregnancy but only 24% in late pregnancy, while milk producing parenchyma cells represent 40% of the gland in early pregnancy and 76% at 145 days of pregnancy. Lérias et al. (2014) reviewed the mammary gland morphological patterns underlying milk production during the lactation cycle for goats. No information could be located on udder characteristics of Angora goats and their relationship with milk production, parity and nutrition management.

It is clear from a review of the literature that the production and composition of Angora goat milk is poorly characterised, the net energy requirements for milk production are unknown and the responses of lactating Angora goats to nutritional manipulation are poorly quantified. Research in southern Australia on annual pastures has also shown that non-breeding Angora goats face energy restrictions from summer to winter (January to August) (McGregor, 2010). Given that most breeding Angora goats are managed to kid during the period May to September (winter-spring), it is highly likely they will experience energy restrictions given the physiological requirements for pregnancy and lactation. A series of investigations into the effects of both mid pregnancy and postnatal nutrition of Angora does on productivity and kid development were conducted using a replicated experiment. This report is focussed on milk production and composition, energy requirements for milk production and udder development.

Section snippets

Design and nutrition treatments

The design was 3 levels of mid pregnancy (MPN) × 2 levels of postnatal nutrition (PNN) providing 6 nutrition patterns. Replicates were 17 randomised live weight and parity blocks each of 6 does. Does were randomly allocated to one of the 6 treatment combinations prior to the experiment commencing. The total of 102 does included 24 twin bearing does. MPN treatments were implemented from days 47–105 after conception as follows:

Control (C) – fed to mimic the usual live weight loses of goats and

Milk production

The mean and ranges in milk production and milk solid composition are summarised in Table 1. Average milk production was highest one week after kidding compared with later stages of lactation, declining from 2.16 kg/d at day 8 to 0.83 kg/d at day 90. Fat corrected milk production declined from 3.99 kg/d at day 8 to 1.38 kg/d at day 90. The maximum milk production for individual does remained similar between days 8 and 90 of lactation.

Milk production was affected by PNN at days 21 and 42 of

Milk production

Maximum daily milk production occurred on day 8 of lactation. Milk production then declined to relatively constant levels between days 21–42 before declining to day 90. This finding should not be surprising as Anderson et al. (1981) demonstrated that peak numbers of milk producing cells in dairy goats are reached by day 5 of lactation. However, these findings differ from the accepted shape of the daily milk production curve in dairy goats, which is an increase to a peak at about 6–8 weeks,

Conclusions

The main factors affecting milk production were postnatal nutritional practices and parity, while postnatal nutrition also had some effects on milk composition and milk energy value. Better fed goats and does rearing twins produced more milk compared with restricted fed does and does rearing single kids. Both milk production and milk fat composition were substantially greater than earlier reports for Angora does. Generally, the lactation peaked at day 8 and declined thereafter, although it

Acknowledgements

The Victorian Department of Primary Industries, the Rural Industries Research and Development Corporation (Project DAV42A) and the Australian Mohair Research Foundation Ltd. funded this project. Without the direct support of Mr Ken Slatter this project would not have been possible. Mr K.L. Butler provided biometric advice. DPI colleagues are thanked for assistance particularly Ms Andrea Howse, Messrs Brendan Scott and Brian Hester.

References (46)

  • J.L. Linzell

    Measurement of udder volume in live goats as an index of mammary growth and function

    J. Dairy Sci.

    (1966)
  • J. Luo et al.

    Prediction of metabolizable energy and protein requirements for maintenance: gain and fiber growth of Angora goats

    Small Rumin. Res.

    (2004)
  • A.P. Mavrogenis et al.

    Estimation of the energy value of milk and prediction of fat-corrected milk yield in sheep and goats

    Small Rumin. Res.

    (1988)
  • B.A. McGregor et al.

    Growth and production of lactating Australian feral does and their Angora cross kids when fed oats with urea or lucerne chaff

    Small Rumin. Res.

    (1988)
  • B.A. McGregor

    The effects of nutrition and parity on the development and productivity of Angora goats: 1. Manipulation of mid pregnancy nutrition on energy intake and maintenance requirement, kid birthweight, kid survival, doe live weight and mohair production

    Small Rumin. Res.

    (2016)
  • B.A. McGregor

    The effects of nutrition and parity on the development and productivity of Angora goats: 2. Effects of six combinations of mid pregnancy and postnatal nutrition on energy intake and doe live weight, body condition and mohair production

    Small Rumin. Res.

    (2017)
  • D.J. Mellor et al.

    Effects of maternal nutrition on udder development during late pregnancy and on colostrum production in Scottish Blackface ewes with twin lambs

    Res. Vet. Sci.

    (1985)
  • P. Morand-Fehr et al.

    Nutrition and optimum performance of dairy goats

    Lstk. Prod. Sci.

    (1978)
  • P. Morand-Fehr et al.

    Composition and yield of goat milk as affected by nutritional manipulation

    J. Dairy Sci.

    (1980)
  • P. Morand-Fehr et al.

    Influence of farming and feeding systems on composition and quality of goat and sheep milk

    Small Rumin. Res.

    (2007)
  • I.V. Nsahlai et al.

    Metabolizable energy requirements of lactating goats

    Small Rumin. Res.

    (2004)
  • D.A. Redmer et al.

    Effect of nutrient intake during pregnancy on fetal and placental growth and vascular development

    Dom. Anim. Endo.

    (2004)
  • T. Sahlu et al.

    Influence of prepartum protein and energy concentrations for dairy goats during pregnancy and early lactation

    J. Dairy Sci.

    (1995)
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