ABSTRACT
This study was conducted to determine the effect of feed supplementation during the postpartum period on the growth and reproductive performance of 40 grazing Sanga and Friesian x Sanga cows in the coastal savannah zone of Ghana. Twenty out of the total of 40 cows (10 Sanga and 10 Friesian x Sanga crossbred cows) were supplemented with 2.5 kg of concentrate per day during the period of study. All cows were weighed weekly and scored for body condition once every week using the 9-point scale (1= very thin to 9 = obese). Also, partial milk yields of all cows were determined daily during the study. Blood samples were taken from cows from week 1 to 16 postpartum and processed for plasma. The concentrations of blood metabolites [glucose, total protein, albumin, globulin, triglycerides, urea, non-esterified fatty acid (NEFA) and beta-hydroxybutyrate (BHB)] were assessed at two-weekly intervals (weeks 1, 3, 5, 7, 9, 11, 13 and 15). Resumption of postpartum ovarian cyclicity was determined by measuring progesterone concentration in the plasma from week 1 to 16 in the cows. Cows were classified as having resumed ovarian activity when a plasma progesterone concentration of ≥ 1.0 ng/mL was recorded for two consecutive weekly samples. In the current study, there was no significant differences (P
> 0.05) in the body weight gain and body condition score of supplemented and non- supplemented cows. Supplemented cows had higher partial milk yield than their non- supplemented counterparts (2.07 versus 1.60 L/day; P < 0.001). Sanga cows tended to have better body condition score (7.50 versus 6.84; P < 0.079), but lower milk yield (1.61 versus 2.05 L/day; P = 0.001) than the Friesian x Sanga cows. Supplemented Sanga cows recorded a lower milk yield than the supplemented Friesian x Sanga cows (1.67 versus 2.50 L/day; P < 0.001). With respect to dietary regime, supplemented cows recorded higher total protein (86.7 versus 81.3 g/L; P = 0.007) and globulin (53.0 versus 47.7 g/L; P = 0.014)
than non-supplemented cows. Sanga cows had higher glucose (4.43 versus 4.09 mmol/L; P = 0.027), total protein (84.0 versus 73.1 g/L; P < 0.001) globulin (47.5 versus 40.1 g/L; P < 0.001), but lower triglycerides (0.25 versus 0.27 mmol/L; P = 0.003) and progesterone (0.58 versus 3.79 ng/mL; P = 0.023) concentrations than Friesian x Sanga cows. Supplemented Sanga cows had lower progesterone concentration than supplemented Friesian x Sanga cows (0.06 versus 6.11 ng/mL; P < 0.001). The interval from calving to resumption of ovarian activity was similar (P > 0.05) in supplemented (53.5 ± 6.27 days) and non-supplemented cows (63.0 ± 8.33 days), however, supplemented cows had lower proportion of non-cycling cows than non-supplemented cows (20 versus 55%; P = 0.022). Also the interval from calving to conception (days open) was shorter in supplemented than non-supplemented cows (95.8 ± 2.96 versus 106 ± 2.83 days; P = 0.032). Friesian x Sanga cows had higher progesterone concentrations at 1st progesterone rise (3.34 ± 1.39 versus
1.32 ± 0.09 ng/mL; P = 0.032) and shorter interval from calving to conception (96.7 ± 2.96 versus 106 ± 2.38 days; P = 0.042) than Sanga cows. Supplemented Friesian x Sanga cows resumed ovarian activity earlier (43.3 versus 67.7 days; P = 0.032) and had shorter interval from calving to conception (92 versus 102.7 days; P = 0.052) than supplemented Sanga cows. In addition, all (100%) the supplemented Friesian x Sanga cows resumed ovarian activity while 40% of the supplemented Sanga cows did not resume cyclicity during the period of study. Based on the resumption of ovarian activity, cows were classified as Early- cycling, Late-cycling and Non-cycling. For Sanga cows, 6 resumed ovarian cyclicity early (by 56 days postpartum), 5 resumed ovarian activity late (within 57-112 days postpartum), and 9 failed to resume ovarian cyclicity (by 112 days postpartum). For Friesian x Sanga cows, 7 resumed ovarian cyclicity early (by 56 days postpartum), 7 resumed ovarian activity late (within 57-112 days postpartum) while 6 failed to resume ovarian cyclicity (by
112 days postpartum). Early (2.54 L/day) and Late (2.01 L/day) cycling Friesian x Sanga cows had higher (P = 0.011) milk yield than Non-cycling (1.61 L/day) cows. Early-cycling Sanga cows had lower total protein than Late-cycling and Non-cycling cows (76.8 versus 89.3, 83.1 g/L; P < 0.05). Globulin concentration was also lower (P < 0.05) in Early (42.6 g/L) than Late (54.2 g/L) and Non-cycling (49.7 g/L) cows. Partial correlation coefficients among concentrations of the plasma metabolites, glucose, total protein, albumin, globulin, triglycerides, BHB, NEFA and urea indicated negative and significant correlation between glucose and total protein (r = -0.255; P < 0.01), globulin (r = -0.200; P < 0.01) and triglyceride (r = – 0.2550; P < 0.01). Total protein was significant and positively correlated with albumin (r = 0.371; P < 0.01), globulin (r = 0.763; P < 0.01) and triglyceride (r = 0.485; P < 0.01). Albumin was significant and negatively correlated with globulin (r = – 0.317; P < 0.01), but significant and positively correlated with triglyceride (r = 0.473; P < 0.01), BHB (r = 0.218; P < 0.01) and NEFA (r = 0.183; P < 0.05). Globulin was positive and significantly correlated with triglyceride (r = 0.166; P < 0.01), while triglyceride was significant and negatively correlated with urea (r = -0.119; P < 0.05) and NEFA (r = -0.188; P < 0.05).
The results from this study indicate the beneficial effects of feed supplementation in terms of increased milk yield, improved metabolic status, less cyclicity problems and less days open. The beneficial effects of feed supplementation to the Friesian x Sanga than Sanga cows in the production environment was also demonstrated.
LIST OF ACRONYMS
AGTR Animal Genetics Training Resource
AHDB Agriculture and Horticulture Development Board BCS Body Condition Score
BHB Beta Hydroxybutyrate
BW Body Weight
DMI Dry Matter Intake
EB Estradiol Benzoate
eCG Equine Chorionic Gonadotropin
FSH Follicle Stimulating Hormone GnRH Gonadotropin Releasing Hormone GSH Ghana Shorthorn
hCG Human Chorionic Gonadotropin
IGF-1 Insulin-like Growth Factor-1
ILCA International Livestock Centre for Africa LH Luteinizing Hormone
MoFA Ministry of Food and Agriculture NEB Negative Energy Balance
NEFA Non-Esterified Fatty Acids
PHGPx/GPX4 Phospholipid Hydroperoxide Glutathione Peroxidase SRID Statistical Research and Information Directorate WASH West African Shorthorn
CHAPTER ONE
INTRODUCTION
BACKGROUND JUSTIFICATION
Livestock production provides vital resources of economic and social support to most people in Africa (Hadush et al., 2013). It plays important roles including the provision of protein in the diet (meat and milk), manure for maintaining soil fertility, traction for crop production and as a source of income (FAO, 2014). This contributes to improving food security and alleviating poverty. There is presently increasing demand for livestock products especially in developing countries due to increasing population and income levels. Considerable improvement in feeding, management strategies and genotype of the existing ruminant livestock will be required to increase livestock productivity to meet this increasing demand (Thornton, 2010). Currently in Ghana, the demand for livestock and its products is increasing. However, local production is able to meet only about 30% of the current demand resulting in high importation of livestock and livestock products from neighbouring countries and overseas to cater for the shortfall. For example, 42, 536 metric tons of frozen meat and dairy products were imported into the country in 2016 (SRID, 2016).
Cattle production constitutes a popular aspect of livestock production in Ghana as in other tropical countries. In Ghana, most cattle are grazed extensively on natural pasture without feed supplementation. A major challenge in this system of over dependence on natural pasture without feed supplementation is the seasonal variation in pasture availability and nutritive value (Hills et al., 2015). The protein and energy content of natural and tropical grasses reduce drastically during the dry season limiting forage
intake and animal performance due to ineffective microbial protein synthesis (Pulido et al., 2009; Hills et al., 2015). Cows are therefore not able to meet their nutritive requirements. There is therefore the need to improve nutrition of cows by providing supplementary feeds during periods of pasture or nutrient deficit to manage deficits in pasture supply, increase dry matter intake and improve productivity as has been suggested in a review by Hills et al. (2015).
Adequate nutrition influences fertility in cattle directly through the supply of specific nutrients required for processes of oocyte and spermatozoa development (Robinson et al., 2006) and synthesis of metabolic hormones [Growth hormone (GH), luteinizing hormone (LH), insulin, insulin-like growth factor – 1 (IGF-1) and leptin], and other nutrient-sensitive metabolites in blood [nonesterified fatty acids (NEFA),β– hydroxybutyrate (BHB), glucose, total protein, albumin and globulin] that are required for ovulation and pregnancy (Diskin et al., 2003; Konigsson et al., 2008; Giuliodori et al., 2011; Samadi et al., 2013; Damptey et al., 2014). Inadequate nutrition during the postpartum period can increase the incidence of anoestrus in cows due to its suppressive effect on LH pulse frequency, and a reduced oestradiol production from the dominant follicle which then undergoes atresia rather than ovulation (Roche 2006; Peter et al., 2009). Poor reproductive performance reduces herd profitability by prolonged calving interval which results in low milk production per cow and fewer calves born per year, increased culling as a result of infertility resulting in increased replacement, labour, semen and veterinary costs (Roche, 2006; Kafi and Mirzaei, 2010).
The extensive system of cattle production in Ghana rely mainly on local breeds, which produce less milk per cow and also have low lactation milk yield. Crossbreeding of indigenous breeds with exotic breeds has been used to improve milk yield and reproductive performance of local breeds through the exploitation of high genetic potential for milk production of exotic breeds and the adaptability to local environment of indigenous breeds (Heins et al., 2008; Sorensen et al., 2008; Walsh et al., 2008; Galukande et al., 2013). The use of the Sanga and Friesian x Sanga in the extensive grazing cattle production system in the coastal savannah zone of Ghana for meat and milk production is popular (Obese et al., 2013). However, these breeds suffer nutritional deficiencies resulting in poor growth, low milk yield, delayed resumption of ovarian activity, extended calving intervals and low conception rates (Sottie et al., 2009; Obese et al., 1999; 2010; 2015a). For cows to achieve maximum productivity under the extensive grazing systems in Ghana, the provision of appropriate supplementary feedstuffs to complement nutritional needs holds promise. Improvements in the productivity of cattle grazing tropical natural pastures has been achieved through the use of concentrate supplementation in some studies (Rekwot et al., 2004; Karikari et al., 2008; Pulido et al., 2009; Filho et al., 2014; Idris et al., 2014; Selemani and Eik, 2016; Obese et al., 2018).
Comparative studies are limited presently on the effect of feed supplementation on growth, milk yield and reproductive performance of Sanga and Friesian x Sanga cows in the coastal savannah zone in Ghana (Teye et al., 2010; Obese et al., 2018). Teye et al. (2010) reported that grazing Friesian x Sanga cows had better growth rates than their Sanga counterparts when the two breeds were supplemented with energy based concentrate in the coastal savannah zone. Also, Obese et al. (2018) evaluated the effects
of feed supplementation on growth rate, BCS, milk yield and resumption of ovarian activity in Sanga and Friesian x Sanga cows for a relatively shorter period of 10 weeks and reported that feed supplementation improved milk yield and body condition score but not resumption of ovarian activity. The influence of feed supplementation on intervals from calving to conception, pregnancy and the roles blood metabolite concentrations play in hastening the resumption of ovarian activity were not assessed in the above studies. Factors including type and amount of supplement fed and length of feed supplementation have been reported to influence productive performance achieved by cattle (Mtenga and Kitalyi, 1990; Filho et al., 2014; da Silva et al., 2017).
This study therefore, evaluated the effects of feed supplementation for a period of 16 weeks postpartum on body weight (BW), body condition score (BCS), milk yield, metabolic status, resumption of ovarian activity and conception in grazing Sanga and Friesian x Sanga cows during the postpartum period. Also, relationships among BW, BCS, milk yield, blood metabolite concentrations and resumption of postpartum ovarian activity were assessed. Information from this study would guide in the formulation of management strategies to improve productivity in these two breeds.
Hypothesis
- Feed supplementation of Sanga and Friesian x Sanga cows grazing natural pasture would improve milk yield, growth and reproductive performance.
- Resumption of ovarian activity will be associated with milk yield, BCS and metabolic status in cows.
General objective
The main objective of this study was to evaluate the effects of feed supplementation postpartum on BW, BCS, milk yield, and reproductive performance in lactating Sanga and Friesian x Sanga cows grazing natural pasture.
